Obviously it'd all have been a bit easier if PT/BG had not forced in the True Love between Harry and Murphy. Early installment weirdness or not, it was treated as a minor Big Deal that Harry had found True Love, because it was rare. A side story had given us the werewolfy True Love on the side, but overall, it was rare so any explanation could explain why Harry wasn't protected here.

Obviously we had no way to go back there, so yeah, here we are.

I, personally, would've found the fact that Harry was dating-for-marriage a perfectly fine excuse why he was no longer truly committed to his True Love, but the book didn't go there.
All in all, bit disappointing. But the book was fine, so I'll just class this as 'weird, probably wrong by old canon, but eh.'

If they were the same Nic, as Kurtin suggested Nicodemus could have been a very common name.  It doesn't matter if he was important at the time or not, but somehow he got tied both to the noose and one of the silver coins with one of the Fallen entrapped inside.  Jim is either leading us down a rabbit hole of implied meaning, or Nic somehow has direct or indirect ties to Judas.

There is indeed one historical Nicodemus outside the bible, apparently (though some scholars suggest they are the same, I think that's reaching... the first was accomplished around the year 30, the second Nicodemus was active around the year 70). And wikipedia mentions it's not sure if the name has Hebrew or Greek origins. So trying to answer which Nicodemus, and why, seems to risk a rabbit hole...

  No, I think the whole Denarian thing will end up going against Marcone's grain.  Andruiel pulls it off with Nic fairly well, Nic still believes he has an equal partnership with Andruiel.  Lasciel tried to convince Harry that that was the kind of partnership he could have with her if he accepted the coin.  However thanks to his inadvertent soul gaze early on when we first meet the Denarians he knows that the host is really the slave of the fallen trapped in the coin, or he feared that.  Based on that knowledge Harry stanchly refused to accept the coin.  I don't think Marcone likes to be or wants to be a servant to Namshell, at the moment he maybe convinced he is in the driver's seat, but I think a day will come when Marcone will realize he isn't in charge of anything,that's the day he will regret his choice.

Regret it, sure.

But I feel the seductiveness of the Fallen would suffer if that regret were sufficient for Marcone to slip the noose and ditch the coin. We already saw Nicky almost redeemed, Harry and Sanya got out... adding a succesful Marcone redemption just feels like it needs way too much buildup. Unlike a Marcone who, like in Battle Ground, works for good despite still being in the clutches of the Fallen.

I am relatively-confident Mirror!Murphy will be alive; simply because of the vast opportunities it gives Jim to further torture Harry.

Early-books Harry was still giving Murphy lots of stay-alive info (albeit limited/incomplete), and I expect that didn't stop completely when he made the Choice.  Remember that Murphy got so deeply into the supernatural because of Harry.  Without Harry there, opening the doors he opened, Murphy's likely to have had shallower, less-dangerous encounters. 

Alternatively, maybe Mirror!Murphy teamed up with Michael, who -- while (mostly) not as clued-in as Harry -- had much more info than Murphy!

If torturing Harry is the point, obviously Murphy will be happy and safe, and be absolutely murderously angry when she sees Harry.

So yes, teaming up with the Knights of the Cross to actually deal with supernatural threats Mirror!Harry doesn't deal with properly, cleaning up his mess... that would sound just the kind of torturous that Harry needs to see. His Choices have Consequences, and maybe even the RIGHT choice in GP has a BAD influence on someone he loved.

I don't recall reading about her. She wasn't in Mab's Sidhe legion that got glamoured, she wasn't in Molly's reinforcements.

While I appreciate the idea, IF Morgan knew who Mac was (approximately), his being paranoid about it tends to put an upper limit on Mac's power.

A random Angel that is out? Sure, could see that. A former Archangel who dropped his mantle into something else? Maybe, though a sign of Morgan's overactive paranoia. But literal TWG or TWC? Seems a bit too high up the power ranks to let any threats be about in his demesne.

Mesopotamia / middle east. See what the Gatekeeper and his fellows have made of the big nasty things that the old tales speak of.
A place like Göbekli Tepe is screaming out for some deep dark ritual. Of course it does run the risk of drawing too deeply on Abrahamic religion to 'paper over' the cracks without having to pick if it's all true or just so from a certain perspective.

The Vatican. See if they've topped Hades - if there's one thing the files have been big on it's comparing humanity to the big nasties... and usually humanity comes out on top, somehow.

Subsaharan Africa. I have no idea of the mythologies of the region, and I think Dresden Files would be a great intro. Even if it would, no doubt, fly in the face of half the themes actually there.

Yes, they do appear civilized, but are they really?  They are cultured, clean, rich, attractive, so they are allowed to thrive, we think of them as civilized.  However these are the same beings who will suck the life out of a mortal by feeding upon his or her emotions. This a group of beings that think of vanilla human beings as "kine" or prey to be fed upon.. This is the group that would imprison the little folk so they can have nice colorful lanterns at their parties.  So as long as they have a source of food, and can create their own "civilized" islands they can thrive in a post apoplectic world as well as the Black Court in my opinion.

Eh, I could see some deluded megalomaniac thinking that, but not the sophisticated strategists that actually lead the White Court. It's easier to prey on a thriving species over one that's marginalized and you have to actively farm.

Humans also started farming fish on a serious scale only when the seas stopped providing quite so plentiful.