Hi! Glad to see you liked it. I've got no definitive answer, but here's how I'd deal with your stuff.
- First of all, I don’t really get the Operator’s gigs and crew. What happens with a gig if you succeed, do they disappear or stay? Is Improvement the only way to get new gigs or can you get them any other way (other then, I guess, through the fiction)? And the crew... Is there anything mechanical about the crew? What do they do (as crew members), how do they influence the Operators work?
Not having any operator at my table, I can't say for sure. Still.
Gigs stay as long as nothing make them burst. Remember: prescriptive AND descriptive. So let's say you have a bodyguard gig and you babysit Uncle's daughter III. If III gets shot in the head, or Uncle suffocate on a mutant chicken bone one day and nobody's paying you anymore, the gig's out. And even if your operator doesn't blow any advancement on the "get more gigs" line but still broke a contract with the nomads to escort their convoy once a week to the city's ruins and back, he'd get the gig.
The crew is simply a bunch of NPC (or PC) the character works with. If as a MC, honnesty and prep demands that Mox tells your fellow operator to go fuck himself because there's no way she'd work with him after he double-crossed her last session, it's up to the PC to work the problem with what he's got: seduce/manipulate Mox, get her something that she wants, go aggro on her, or simply talk about the problem with her or something.
- The Chopper’s gang got a Vulnerability, do I get to activate it or is there a rule for when to do it?
You activate it by doing the MC's move: activate their stuff's downside. I also use them to decide which orders the gang won't follow (inciting the chopper to impose their will on the gang) and what they do when they're idle.
- The Gunlugger counts as a gang... In what way?
When the Gunlugger's in a battle, they count as a small gang to determine the harm they deal and take. So a NOT TO BE FUCKED WITH gunlugger going against a small gang will inflict full damage to the gang and the gang will not get a +1harm. Against a medium gang, they'll deal harm-1 and take only harm+1. Against a lone fucker NPC, the NPC's pretty much fucked : full damage (3-harm +1harm because it's like a small gang going against one guy, so 4-harm) minus that NPC armor.
- When shit’s going down and people are fighting, how is harm distributed? Say that Glenn is fighting against two others, he rolls to seize their lives by force and he succeeds with his roll - does he inflict his harm on both of his enemies, and do they both get to inflict their separate harm on him? And while we’re on the subject, if Glenn’s enemies survive and are still in the game, can Glenn roll another Seize by force to inflict more harm, and another and another - or should one roll solve the whole fight?
Two guys ? Well, you get to decide if they outnumber Glenn. If so, they count as a small gang and each recieve harm as established by Glenn's weapons, minus one for being a bigger gang than Glenn's lonely ass. When they deal damage, they do so as a gang: as established, with +1harm because there's two of them.
But Glenn's a gunlugger, right ? He's all badass and two guys don't really outnumber him. So each one take full harm as established by Glenn's weapons and moves, and those guys' armor. When it's your turn, either you don't feel like making a hard move on Glenn and only one of them inflicts damage (if that's what you want to make of your move), or you decide to go hard move on Glenn because he's walked straight into a trap you established through fiction and both of them inflict damage on Glenn, minus Glenn's armor.
About rolling seize by force multiple times: do what honnesty demands. When the player's character do things that seem like seizing something by force or securing their hold on something sure, let them make the move. If not, try to see what they're trying to do. Ask questions! "What are you trying to do, here? Running for the door? Killing everyone of them motherfuckers? Sending a message?" Follow on the answer. And if a PC tells you straight on "I seize the exit by force!" say "cool! What do you do?"
A thing about harm: remember, you make a move when
a) a player misses a roll or
b) they're waiting for you to say something.
MC's moves work on NPCs too. And
Inflict harm (as established) is a MC move. So when a player's all "Imma KILL that guy!" and there's no reason he shouldn't be able to do it and the player's all "what happens next?", don't be affraid to inflict harm on the poor guy as established by the PC's gun! It's fun! Be a fan, look through crosshairs and all that!
- When to PC:s fight, who rolls the Seize by force?
Let's say Dremmer has a box, and Rex wants it. Rex's player tells you "fuck it, I'll take that box and I'll break Dremmer's face if I have too" and Dremmer's player is all "no way !" So Rex rolls +hard to take the box by force, but Dremmer's player rolls +Hx of Rex on his sheet to interfere and hopefully gives Rex a -2.
If the box is sitting there and Dremmer and Rex are looking in each other's eyes, the first to talk gets to roll +hard. The other can always roll +Hx to interfere.
Now, remember that moves snowball. As long as nobody has a definitive hold of the box, everybody gets to try to take it by force, or try to put themselves in a position from where they can go aggro onto the box holder, or manipulate them to give that box away, etc.
That's for when PCs fight for something. Now, if they're fighting because one wants the other to do something and the other doesn't want to, that's a go aggro right here. If the victim's all "hell NO" get them roll +Hx to interfere and if the attacker misses their roll, the other one's got the drop on them or something. On a miss, hell, you get to make a move, so you might even
turn their move against them and say something like "you're about to get your gun against Dremmer's forehead but he's too quick for you, man. Dremmer,
your gun is on Rex's crotch. You can go aggro on him right now, as if you'd rolled a 10+. What d'you want Rex to do?"
If that's just a case of "I've had it with Rex. I pull my gun and shoot that fucker in the head" you might choose to a) make Dremmer go aggro on Rex and what Dremmer wants is Rex to roll over and die (inelegant if you ask me, but a legit ruling), b) have Rex act under fire, and the fire is "Dremmer cap your ass and inflicts harm as established" or c) choose, as a MC move, to inflict harm as established by Dremmer's gun, like Rex's all tied up or can't see Dremmer scoping on him from the clock tower with his high-powered sniper rifle. As usual, if dice are rolling and the victim can interfere, have them roll +Hx.