...Palpatine had planned for Sith artifacts to be dropped in jakku core via mining shaft which would initiate explosion and result in the subsequent destruction of planet and ships in orbit. ....

I think this is the key to Rey.  A force sensitive child growing up in a sith and death tainted environment.  You could pull at KOTOR 2- Jedi General thing, where she (as a child) cut herself off from the Force.  Her contact with Kylo made a connection back to the force for her. 

I have a running theory that "Mirror Mirror" is going to be a return to the events of Proven Guilty, where mirror Harry and normal Harry are manipulating things behind the scenes to keep or change the timeline.

And I fall into the "human colony spacecraft" camp.

Food grown in vats. 
Habble = habitation bubbles- square living areas inside a round bubble, one with a transluscent dome.
Ventilation, water, and waste tunnels and pipes. 
The black horse inn had the 'horse' part referred to as a mythological animal. 

 I think that colonists from Earth landed there, only to find the combination of etheric energy and atmosphere caused rapid degradation of steel and iron.  So they buried the colony ships on the tops of mountains and clad all the metal in some kind of ceramic composite, creating 'spire-stone'.

My belief is that this is a retro-future world.  Imagine a world where settlers from Earth arrived ages ago.  They planned to live in their space-ships for a decade or so until they got habitable natural cities built.  But they found that the atmosphere, somehow, was corrosive to their metal. 

So the spires are giant, tube-shaped spaceships covered in earth to protect their exteriors. 

(1) What is Nic trying to get his hands on and why?
I believe that it will be some object that will allow some control over the seasons, as a tie in to the Persephone/Demeter myth.  Manipulating the seasons is mucking with Mab and Titiana’s powers.  Also, weather extremes are tied to violence and upheaval, which Nic would love.  This is, of course, not what he TELLS anyone.  This will be a quest for a religious relic to restore souls, which will entice several others to join him (see below).

(2) Does he have a specific plan for using Harry or did Mab twist his request?
I have to believe that Harry as Winter Knight and his defense of the island and offing of Maeve are all well known by now. He knows that Harry believes some of the Denarians are not on the same team as Nic.  Thus, this will be an “anti-adversary” quest on the surface.  Thus, Harry is the logical choice. 

(3) Who else does Nic recruit?
At least one more Denarian besides Tessa.  I suspect Lasciel.  I can see Mavra making a re-appearance.  Being dead and all she would be good, and if the Black Court has ties to the Outsiders as some suspect, then she could have her own motives for joining.  Of course, everyone will not be able to kill Harry off hand, but they wont go out of their way to stop him from doing something  stupid. Then there will be Marcone.  Yes, he will be there.  The Denarians will try to recruit him, but he will be looking to continue his efforts to fix that girl.

(4) Who will Harry bring in?  Who will interfere?
I assume Hades is part of the Never Never somewhere.  Harry is starting to realize he has power, but lacks knowledge.  As such, I think he calls on Bob.  We saw how powerful Bob was when battling Necro-Bob.  Plus, he knows a ton.  Bob is the least well known of his allies, so it would be a surprise to them.  I expect at least one interference by Summer- both because of Lily’s death and because they have to oppose actions by Winter.  I could see Fix showing up again.  Other than that, I expect most of his allies to stay out of it- Harry knows this is a bad deal and wouldn’t pull them in.  However, I expect Harry to use them for a big surprise at the end.  Since Bob has learned about the internet, he could be using it to tell them everything, and setting up an ambush at the end.

(5) Knights of the Cross?
I fully expect Sanya to interfere as it his job to oppose the Denarians.  That will likely happen early in the story- Nic will probably steer events to make it happen.  I also think this is the book where Murphy will pick up the Sword.  With her running the Justice Leage of Chicago, it is only a matter of time before she assumes the Arthur role and the FLC changes into Knights of the Round Table, version 2.

(6) What has Mab got going on?
First, she is repaying Nics debt.  I think Nic found out one of the other Denarians was part of the attack on Arctic Tor- an attack designed to free an infected Lea so she could displace Mab.  Nic lent another Denarian to Mab to foil the attack in exchange for eliminating the corrupted Denarian.  But whoever [Lasciel] it was escaped, so Mab owes still.  Thus, that Denarian will be on Nic's crew.  So Harry can think he pulled a fast on on Nic, and Nic can let that Denarian be killed and his hands still be clean.  Second, neither summer nor winter want Nic to get his hand on the McGuffin, so by sending Harry it allows Summer to keep attacking the group and weakening it without revealing that Mab knows Nic’s real objective.  Third, well, see the next item.

(7) What’s with the headaches?[/b]
I think it has been pretty well telegraphed that it is Lash.  By renaming the shadow of Lasciel to Lash he changed it.  Uriel hinted at the power of names in Ghost Story.  I think that, in Hades, Harry will lose the earring.  This will free Lash, who will take over Harry and use him to wage war on Lasciel.  If Lasicel wing, Lash dies and Harry is free of it.  If Lash wins, she will drop the coin and take possessin of the body- gaining Harry another knowledgable (and endebtted) ally.  All part of Mab’s plan.

(
After besting the forces and traps of Hades, Nic reveals his item and tries to force his will upon the Queens.  They, in turn, reveal they knew his objective from the beginning, and have agents in place- return of eldest Gruff?  OF course, Nic suspected it and calls in Denarian reinforcements.  Which, in turn, was exactly what Hades expected him to do.  Hades wants the Denarians back under his roof, so to speak, and throws in with the Queens. 

(9) WAG theories
A) Harry will have a moment with the shade of Susan, where he finally receives forgiveness for what he did.  He will have a moment where he could sacrifice his role in the quest to ‘save’ her shade, but will leave her to her fate. This will likely be a test by Hades.
B) At least one Denarian coin will already be in the hands of Hades.  Likely one of them from the attack on Arctis Tor and NOT Thorned Namsiel’s.  This was the payment of Mab to Hades to not take Harry’s spirit right away.
C) Duckie’s infamous Mavra/Harry  poetry will be referenced somehow- likely by her constantly coming on to Harry.

(10) Extra Credit
-Harry will sing or hum “Highway to Hell”.
-Harry will reference Ocean’s Eleven in a snarky comment to Nic- like saying he doesn’t look like Clooney.  Nic will return snark, saying he always thought he looked like Sinatra- referencing the original Ocean’s 11.
-Molly will NOT be seen in person- Mab is keeping the two apart. 
-At some point while wandering the maze, Harry will lament he didn’t bring either a ball of string or a piece of chalk. 
-At some point during the trip someone will suggest splitting up and Harry will reply along the lines of “Dungeon crawl rule #1- don’t split the party.”
- Early on, Harry will find out that Mister died of natural causes.  He is a cat, after all, and a decade and a half for an outdoor cat is unlikely. 
- Harry will get to meet the spirit of Mister and have his tearful goodbye.

I would like to see Jims version of Tinkerbell (since my other picks have been taken)

I think we have met her.  She was leading the charge to kill Harry in Winter Knight.  After all, Toot-toot and the rest do seem like lost boys....

1 ) Harry usually has a few supporting characters in each book.  Who do you think will be the main sidekick in Cold Days and in what way will they help?  Who else will have a significant contribution to the plot? 

The main sidekick will be Herbie, the living embodiment of the Blue Beetle.  It will be sarcastic and tempremental, but be able to navigate through the nevernever like no one else.

2 ) At the end of Ghost Story, Harry has said goodbye to all his friends in Chicago. 
a. Who will be the first friend to find out Harry isn't dead? 
b. What shenanigans/snark will Harry use when he "re-appears"?
c. Who will have the coolest reaction?
d. Who will have the most touching reaction?
- In each case, remember to specify for extra credit.

2A:  Mister will encounter Harry on one of his nightly wanderings.  Being a cat, he won’t tell anyone.
2B: Each time Harry appears to a friend, they will have a counter-snark or preemptive snark ready, just to steal his thunder.
2C: Molly will have the coolest, initiating a truly epic round of pop-culture reference one-upsmanship.
2D: Mac.  He will hand Harry a beer and say, “thought you was dead.”

3 ) In nearly every book, Harry usually comes up with a new powerup/tool/way of making things go boom.  Given that he just became the new WK, what new abilities will he rely on and which new ability will be the most useful to him during the story (and how)?

Harry will sprout wings on his ankles, enabling himself to fly just above the ground. Oh, and it will give him the ability to talk to fish, which will help out in the BAT, somehow.

4 ) Harry generally has a "Big Bad" to worry about.  In fact, according to the blurb, Harry is going after someone very specific.  Who will that enemy be, and how will Harry take him/her/it down?

Harry’s gonna have a throw down with Santa Claus, ‘cause Mab is tired of being put on his naughty list every year.

5 ) Harry usually faces some sort of "Choice" in every book.  A point where the easy way out will cost his soul/humanity in some way. According to the blurb, this book will be no different.  What will be the most crucial "choice" Harry makes?

Harry will be forced to choose between Coke and Pepsi.  Coke, of course, will be the easy choice, but by choosing Pepsi he will save the world.  Of course, that means giving up on Burger King once and for all.

6 ) As the new Winter Knight, Harry is pretty much garunteed to encounter his Summer counterpart -- Fix.  What will their interactions be?  Will Fix survive?

Squirt guns at 20 paces, with Fix, the loser, being forced to dress like Bugs Bunny in drag for a full year.

7 ) Jim has mentioned that it's about time now to start revealing some of the motivations/dealings of the shadowy figures working behind the scenes (i.e. what Harry calls the "Black Council").  What Black Council secrets/actions will be revealed in this book?

Their dress code, secret handshake, decoder ring, and that the “evil overlords” list is required reading for them.  The last one will send chills into Dresden as he realizes it makes his enemies essentially snark-proof.

8 ) There are many WAG ("Wild A$$ Guess") theories on the boards.  Write up to three WAG theories you believe are correct that will be confirmed (or at least have evidence in favor of) in Cold Days.

The “Molly is Mab” theory:  it will have something to do with matching piercings, I’m certain of it.
The “Harry is a decoy” theory:  Elaine will be relvealed to have been Harry’s mother in disguise all along, leading to some really uncomfortable silences around the dinner table.
The Black Court employee register:  The Merlin will have a heart to heart with Harry, explaining that he really didn’t hate Harry after all.  The Merlin, it seems, believes in the whole concept of “spare the rod, spoil the child” and was only harsh on Harry to make him the best he could be.  He turns out to be a good guy after all. 

9 ) Extra credit:  Write down any prediction about that you think might improve your final score.  Only issues aluded to within Cold Days will be counted.

Harry will visit Chicago, Harry will visit Edinborough.  Harry will complain about the cold.  Harry will go to Burger King.  There will be at least one reference to Star Wars / Star Trek / D&D / The Lord of the Rings.  Harry will build an igloo outside of Arctis Tor and attempt to sell snow-cones to the natives. 

I keep mine on the top shelf in a coffee can labelled "Sesame Alfalfa Cookiees".