I'm not a Burned Over guy, so sadly I cannot help you.  :(

This is conceptually interesting. Thinking back to some of my own games, this could have applied to some of them, but wouldn't have been at all appropriate to others. Much will depend on the nature of you game's psychic maelstrom, but that is largely impossible to know going in because it gets defined increasingly during play (unless everyone agrees to something specific in Session 0, which we've also had happen).

I feel you on the narrative interest part, it can be hard to some up with a set of choices that feel fundamentally equal without having something that is either an auto-take or super situational. I find it's easier with consequences/complications than it is with any kind of buff or boon, but that might just be my MC reflexes being more consistently tuned for coming up with engaging consequences.

To expand a little bit on the last response, the "rules" in Apocalypse World may feel quite a bit different from the rules in traditional RPGs because they concern themselves with different things. I find I almost never need to "bend the rules" in AW because they are sufficiently flexible that it's never really an issue.

The bulk of the MC's principles in AW are about coming up with interesting consequences to the PCs' actions, and in that regard the story is very much the most important bit. Just beware that you're not imposing "plot" on them, as one of your most important principles is "play to find out."

The longest lasting AW campaign I've run capped out at 35 sessions. Of the five original characters, three were still in play (with the other two players having lost a character to death and retired one to safety respectively). We could have gone longer, but the campaign was at a satisfying end point so we wrapped it up. But here's the catch - the players explicitly wanted a slower progression to give them a chance to "inhabit" their characters for longer than you typically et in AW (where 10 sessions in you might be looking at "retire to safety" and "switch playbooks" as those among your dwindling supply of possible advances to left take). The only change we made was to double the amount of XP needed for an advance, and it worked perfectly. As a result it told a "slower" story, but that was by design.

Now, in terms of how to address you specific issue, I think one of the best things that can be done is to "put your bloody fingerprints" all over the allies. You're no longer looking at them through cross-hairs and they are no longer actively looking to mess with the PC - but that doesn't turn them into automatons. They're not suborning their parts to the Skinner's every whim. They still have wants and desires and needs and problems, and just because they're your ally doesn't mean those all stop. Indeed, being the PC's ally might make them worse. What do you do when your allies are competing amongst each other for your attention/favor/love? That warlord who you've turned into your love-toy - how do his goons feel about him "going soft?" Does he still command their respect? So sure, you can turn the Humongous into an ally, but doing so might intrinsically change him, for better or for worse.

As the MC you don't want to be a jerk and undermine what your PC has worked to achieve, but that doesn't mean you need to make their lives sunny and uncomplicated either.

I have to admit that Seize by force already in first edition is the part of rules which is conceptually hardest to swallow for me, as it seems to dilute the boundary between failure and success (you will get harmed no matter what).

Taking Harm is not failure. It is the price of success. Or rather it's the ante to even have a shot at succeeding in the first place. When things have devolved to seize by force or single combat, bullets are flying and the situation is already well and truly out of control. Harm is just what happens to you while you're trying to get yourself out of the mess.

I think you can do it a couple of ways.

First, I don't think the move is intended to be full-on shape-shifting. A strict reading of the move says you may change any or all of your looks, meaning looks associated with your playbook. So you could (for example) go from being a "boy in scrounge wear with an innocent face, bright eyes, and a child's body" to "ambiguous in scrounge wear with a misshapen face, cruel eyes, and a child's body." You will note that there are two elements that don't change - you're always in scrounge wear, and you're always a child.

This is sufficient to fool casual observers or people who don't know you. Say you're pursued through the hold's bustling market. At some point when you manage to break line of sight, you change your looks and Dremmer's goons - who were looking for an innocent-faced boy - totally pass by that weird kid with the misshapen face. Because that's not who they're looking for. The last campaign I ran involved a Child-Thing who (along with several other PCs) effectively got exiled from a community. He (it?) was able to regain entry to that community because no one there really knew him well enough to be able to see the difference, nor did anyone spare yet another urchin a long enough second-look to be able to tell the difference even if they had. And he was feral, so he didn't even need to attract any attention begging for food. He could be socially invisible when he wanted to, which turned out to be pretty rad - mechanical benefit or no.

A looser interpretation of the move would allow you to pick any "look," but at that point if you're talking about mimicking adults I think you're straying pretty far from the central concept of the playbook. And I'd definitely stop short of allowing the move to perfectly mimic a specific person, as IMO there's more to a person's visible identity than their basic look. I don't think perfect visual mimicry is the intent at all.

Also, being able to pick any look raises all kinds of issues with respect to garb - could you just trade your scrounge wear for the Gunlugger's custom homemade armor at a whim? Would that actually give you the equivalent of actual armor? Could you conjure up the skinner's luxe wear? How would you handle gear - especially worn gear? A more open interpretation of the move might be OK, but it's going to take more work on your part as the MC to make calls on a case-by-case basis - and that's generally not good move design (which in turn sort of points me back to the stricter interpretation).

And to answer your last question, if you can't mimic a specific person then blending into a small group of uniformed soldiers is right out, because someone is bound to ask, "Hey, who's the new guy? And why doesn't he have any gear?"

Understand that this is just my interpretation, but when it's talking about a "PC's other NPCs" it's things like the Maestro'D's employees, or if the Angel or Savvyhead have "skilled labor" or whatever.

So as an example the Maestro'D has a crew of people to help run the establishment and taken collectively they are brutes. But maybe one of them (say the bartender Sunny) is a "grotesque," meaning there's something about Sunny that...ain't right. Or maybe the bouncer Bosco thinks he's tough and is a wanna-be warlord, and when he's deep in the fermented algae slurry he talks shit about how he should really be running things.

This means that the NPCs associated with a player's "crap" are assets, but also Threats. Does that make more sense?
 

Just as an aside, #2 is a great way to give players some input into the setting. As in:

"Hold up. When you get to your garage, there's a bunch of jerks there rummaging through your stuff. When they see you, one of them says, 'Where are you hiding Diana? Tells us now, or we kill you dead.' So, who - or what - is Diana, and why do these dudes think you'll know where to find her/it?"

And if the Driver's players thinks for a hot minute and says, "Oooh! Oooh! I know: 'Diana' is the name Dremmer gave to his motorbike, which I stole. But these assholes will never find it here because Bish is hiding it for me," then so much the better. Now you have more information about the Driver, Dremmer, and Bish. You are explicitly letting the player tell you something the character knows and taking it on face value as truth. That can be a ton of fun for everyone involved (including the MC, who is also playing to find out).

FWIW, doing this puts a lot of faith in and pressure on your players, so only do it if you know they can handle it and enjoy being put on the spot to come up with cool new details for their character or the world in general.

@sirien: in regards to your question about who decides which move is triggered, as Vincent says the player has ultimate control over saying what they do (or try to do), but it's incumbent upon the MC to decide if that action is sufficient to trigger a move. So for instance if you say, "I go aggro on the guy," it's perfectly reasonable for the MC to ask for clarification, like, "OK, but hold up - what is it you're actually doing to threaten this guy with imminent violence?" Remember: to do it, do it.

It's fine for the MC to offer suggestions as to what fictional actions might trigger a particular move (e.g. "If you want to use Diana as leverage over Dremmer to get him to do what you want, then yeah, that's totally manipulating him. How do you want to do that?") but the final decision of whether the PC takes the fictional action that triggers the roll is up to the player.