im not too sure bout this but i do believe that transported fuel is transferred to the cargohold of the station first and it refuels itself from the cargo?
Yeah I haven't verified this either buy I know for sure civilian transports will drop fuel off at the station then the military can use it as fuel point, hint hint fuel post at a planetless star. Make sure you put energy collectors on it.
Meh. I put on the bare minimum 1 cargo hold on my base designs including space ports as those use your planets cargo in any case. The only base designs that have more are my Mining/Gas Mining Stations which have at the least 15-25k of cargo space.