Oh yes, fresh air is a MUST. This stuff will kill you.
My comment about air brushes should have come with a qualifier. I started with a harbor freight unit too, along with their airbrush compressor.
Me and my buddy have done several paint jobs using them but quality of the finished job is NOT 100%. Since you'd like to do this once and not have it suck, I've found it pays to buy a top feed (thought I'd hate it, but it rocks).
I also said something else not exactly true and this is supporting your statement about it being "air dry". That would imply that it dries, but in reality is "cures" via a chemical process. I'm sure it would actually kick off under water if I had to prove a point.
Cerakote is an oven cure paint (also catalyzed IIRC). I've never used it, but have considered doing a hand gun slide or two.
I wouldn't think you'd need an FFL to do paint jobs for people, especially if you are doing face to face exchanges. But I'm not a lawyer or a cop, so do your own research there.
Duracoat comes with specific instructions on how long to wait between layers (an hour I think) and have all layers done before 7 days.
You can handle it in an hour and I've even reassembled guns because I wasn't patient enough, but the paint is still very "green" for a number of days.
Here are two of my most recent paint jobs:
It's addicting.
