They do, every exchange.  So I don't really see how a grapple is that much different.  The only difference is that the advantages and disadvantages of a grapple are maintained (such as not being able to sprint or move zones and the grappler being able to add aspects or do damage every exchange) each round unless the victim can break the block in a way that justifies breaking the grapple.

The person putting up the block still has to re-roll every exchange just like a regular block.

I haven't read Fate Core...so I can't really compare.

My biggest complaint about grapple rules is they are too simlistic.  I like the idea of both people in the grapple being able to hurt the other.  The way the rules are are a bit one sided.

You could use the rules as is to make that possible I believe.  Instead of trying to break the grapple, the you could instead set up your own maneuver to initiate a grapple AGAINST the person holding you.  Thus kind of causing both characters to be in a grapple with each other.  This could cause an interesting tug of war of the characters dragging each other around, doing damage, or trying to break the others grapple before their own gets broken.  It would also mean neither could just release the grapple without being stuck in the others grapple.

That's a really good suggestion.  It covers the basic concepts of the world, shows the line between the supernatural and the vanilla world, humorous banter between a down-on-his-luck Wizard and a talking skull, ect.  It's only about 5 minutes long to boot, which means I don't have to expect my players to sit in silence for 15-20 minutes to listen to a single chapter.

I would strongly advise against inter-player conflict in the mechanical sense of the word.  Keep that as role-playing fluff and declairation skill checks, and combine that with compels to represent any conflict between players.  It means your players aren't filling up each others stress and consequence slots, and the losing player possibly getting a fate point can take the sting out of losing.

As for the NPC question: If It's a single NPC helping out, then It's probably best to write them up just like you would a PC, except you as the GM would be controlling them.  As Mr.D already mentioned, anything npc related that couldn't reasonably be written as an NPC would be an aspect.  Which leads in to the tear gas question....

I would make the tear gas a scene aspect that doesn't go away for that entire scene.  The players would get a free tag on it, then would have to spend fate points to take advantage of it after that.  It would basically be a catch all aspect they would almost always have justification to tag for attacks, maneuvers, and defense.  I would also remind you that scene aspects are double-edged and can also be used against the PC's.  If all the PC's are wearing gas masks for example, and an npc manages to rip the mask off a player via a maneuver.  Now the PC has almost no way to invoke the scene aspect, and is now prime compel material to throw a wrench into the entire groups plans.

As for overuse of intimidation, you could bait your players into intimidating the wrong person.  Off the top of my head someone who has armed lackeys.  Give him high Intimidation and an aspect or two like "A Mind like Cold Steel" and "Scariest Businessman on the East Side".  Give him a few stunts, one that allows him to defend against social attacks with intimidation, and one that gives him say a +1 bonus to Intimidate rolls when he's in a position of power against his target.  Calling in his goons as a maneuver/declairation not only gives him a free aspect tag of "Armed Entourage" (potentially giving him a whopping +6 social attack with aspect invokes), but also makes the chance of a physical conflict breaking out if the players aren't careful.

Forcing physical conflicts the players didn't expect or want to get into is the easiest way to discourage abusing Intimidation.

The general public by and large is totally in the dark.  It's been suggested that there are government types that keep incidents under wraps, but that they don't typically get involved with the supernatural world at large, at least not directly.

The supernatural community isn't quite so big on the conspiracy angle.  They take some precautions to not draw attention to themselves, but they more so just bank on the general public's inability to accept the truth, and that they will just make things up to cope.  "That wasn't a zombie I saw, it was just some homeless guy on drugs.", "That couldn't of been a bunch of werewolves, it must of been a pack of wild dogs or wolves that wandered into the city limits."

It's also worth noting that It's an unspoken rule of the supernatural world that you NEVER intentionally get the mortal authorities involved on any large scale.  That It's considered to tantamount to launching a nuke at an opposing nation.

In short, the PC's (and GM) should be mindful of the vanilla population, but they shouldn't let it hobble them either.

Ah, excellent. Thank you so much.

Here's a question: The spell example Entanglement (YS293)... how is that supposed to work. You cast it and if your roll exceed the Target's Athletics roll, then the Aspect BOUND IN PLACE is placed on the target? Does that actually bind them in place? Or does it just put an Aspect on them that can be tagged if they try to run away or something? And how long does it last? Is it one exchange?

It's generally a good idea to ignore all the example spells listed in both books.  A lot of them are horribly worded at best, or downright break the stated rules at worst.

In this case Entanglement is probably a maneuver, as it does specifically state it's an aspect.  Which means it would not physically bind them until you tagged the aspect.  The issue there is you pretty much have to tag for effect instantly, because if he moves you lose your narrative justification.

Then the target of the spell would be unable to move until they (or someone else) takes an action to remove the "Entangled" aspect, probably with another maneuver action.  The difficulty to do so would likely be bases on how much power was put into the spell, 3 is typically the default number for an evocation maneuver.

My question is how would you make apply to him differently than every other character?  Most characters could be affected in some way?

It's a good concept for sure.  I'm just curious as to how you would utilize it to warrant such a huge rebate.  I can see it coming up often if you like making "Joker" style villains.  The kind that rarely fight, but their schemes would kill hundreds (or thousands) of innocent people.

Seems a bit weak even for 1 Refresh. I doubt the bonuses will matter often.

You get the normal Aspect tag when you use this, right? I would assume so, but I could see someone reading the "special Aspect" rules of this Power as an invoke-for-effect. Some people read Venomous Claws that way, after all.

And you should probably specify that it applies to physical consequences. As written it seems to apply to mental and social consequences.

All that aside, should I add this to the list?

I was speaking under the assumption that you would get the standard free tag and could invoke it with fate points like normal.  Otherwise, I agree it needs more teeth to be worth a -1 cost.