Is it possible to hijack a ship during a battle?
if yes they could do that. or if no then they could have bribe special ability.
It is, according to Z3r0x... He told me how once... But you don't keep the ship after the battle, and I doubt a small group people could effectively capture any ship worth capturing.
it would be better to code them in to be like the buzz droids, deployed from shuttles or something and with a much longer loiter time. maybe have them armed with light blasters and concussion missiles?
That could work, but they wouldn't technically be armed with anything.
i think this would be possible for FOC but would it be possible for space troopers be able to come out of ships and start repairing them
Not possible. The closest thing to that would be making them a deployed unit that heals ships, but we won't be doing that... If you want a ship healed, you need to do it at your dry dock.