1) Depends on how you are handling the gun. If it's part of an animated object, then the recoil would be best as an animation sequence. If the gun is an object, then you are probably positioning it every sync, so, when the gun fires, offset the gun a little (i.e. Move Object Up GunID,2), after the normal positioning code. This will then show the gun as offset (recoiled) during the sync, but will return to it's normal position the next sync. If the gun is a limb, but not part of animated object, then you will need manually offset the limb when the gun is fired, and return the gun to the original position afterwards.
2) It will be tough to get into/out of a vehicle. Well, basically, it's not extremely complicated, but it is a lot of work. You would need an animation getting inside the vehicle, and an animation for getting out fo the vehicle, animations for not in vehicles, animations for driving each vehicle. Edit: Then there is the fine-tuning. Making sure everything lines up correctly - i.e. the feet aren't sticking out the bottom of the plane, or the head isn't smashed through the windshield.
3) You got a Klu on this one already.
"Droids don't rip your arms off when they lose." -H. Solo
REALITY II