well i dont know about the last one cannon since its all computer based imo. Probably dont need more than 5-10 people to keep the ship combat ready, but to sustain it combat ready you need alot of people. but you dont do repairs mid combat. not those kind of repairs
but fuel idea would rock. draining itself slowly, not taking up cargo space but you have to land every once in a while to refuel. It would help keeping players in their ZOI