Don't forget to make them make the harm move. If there's any kind of harm that the harm move should be made for, it's being on fire.

One of the most important things to remember when designing moves that allow a character to influence another character's behavior, is to always "pass decision-making onto the victim, the defender, the looser." Go Aggro is a good example of this: the victim never actually has to do whatever it is that you want them to, as long as they're willing to force your hand and take the consequences. Even In Brain Puppet Strings, a move that is literally mind control, follows this rule: You say what you want them to do, and can spend holds to punish them if they disobey, but you can't actually make them do it if they really don't want to, and are willing to eat the harm. Hypnotic is similar: you get holds on them, and as long as you have the holds, they either can't act against you (NPCs), or have to Act Under Fire to do so (PCs), but they decide what they want to do to spend the hold that you have over them.

I've always been rather enamored of the idea of a Brainer becoming an Angel or Battlebabe. As a Brainer, you live sort of on the margins of the community; sure they like what you can do for them, but they're also scared shitless of what you can do to them. If, through play, you manage to win thr community's acceptence, then, bam, Angel. But if the community outright rejects you, then fuck helping people; Battlebabe time.

If the Hocus doesn't have the follower option that gives +growth, but is doing a good job at being charismatic, how would you handle the possibility of acquiring new followers?

If they manage to convince someone or some group of people to join the cult, then they join the cult. But they don't get new converts automatically just for succeeding on their Fortunes roll.

At this point, Dremmer has come to his senses and pulls out his gun and points it at Gritch's face: "What do you do?" Duke's player jumps in and says, "I shoot him." Again I wasn't sure how exactly to handle it, I went with seize by force but I didn't have Dremmer shoot back because he wasn't paying any attention to Duke, he was set on the freaky brainer.

If there's no one fighting back, then Seize By Force isn't really appropriate; part of the point of that move is that no matter what happens, everyone involved is going to get hurt to some degree or another. Remember, inflicting/exchanging harm as established is always a thing that you can just narrate happening without calling for a roll, if the situation makes it appropriate. If you really want to make Duke roll something to pull it off, I'd probably go with an Act Under Fire, with the fire being that Dremmer's trigger finger is just a fraction of a second quicker than Duke's, and Gritch takes a bullet.

Highlighting a stat is basically telling them "do this as much as possible"; Highlighting their good stats is telling them that tonight will be their night to shine.

The Hocus's followers count as a gang if the Hocus uses Frenzy to have them "unite and fight and as a gang (2-harm 0-armor size
appropriate)". Otherwise, no, they're just a disorganized mob who don't act together and consequently don't get to benefit from the gang rules.

Sometimes i would like my npc to react to seize by force not by exchanging harm but doing something different: run away, hold the PC in an arm lock, throwing the antidote into the fire and so on... Ofc if the PC takes definitive hold of something, you can't do that but otherwise could you? Or you just have to exchange harm as estabilished?

In order to do something, you have to do it. If the PC is doing something other than "inflict violence on someone who is inflicting violence back on me, in order to achieve some specific goal", then he's not Seizing By Force. He's doing something else. In the specific cases you mentioned, here's how I handle things:

• "run away" -- Go Aggro. On a 10+, the NPC has a choice: he can either cave and stay put, or suck up the harm and try to escape. If he chooses the later option, and is still ambulatory afterwards (probably only the case if he's wearing armor, given how fragile NPCs are), he gets away. On a 7-9, the NPC barricades himself in somewhere; he certainly hasn't gotten away, but the PC  will have to change tactics if he wants to get at him (technically, I could also have him "back off calmly, hands where you can see", but that doesn't make sense given the situation: if the NPC tries that, the PC will just shoot him). On a miss, the NPC is gone.
• "hold the PC in an arm lock" -- Act Under Fire. The fire is that he gets you in the arm lock. Pretty straight forward.
• "throwing the antidote into the fire" -- Act Under Fire again. The fire is that he destroys the antidote before you can stop him.