Well fortunatly im not blind enough yet to be unable to tell a warship from a transport ship at night, I ment more for telling its nationality.
Yep the bucket system was used for moving shells, however it was still a slow and carefull process, you dont exactly want to drop a 88mm or 105mm shell inside a uboat onto a steel deck. Personaly i think 8-10 seconds is a reasonable comprimise.
I havent had any troubles selecting different shells when the ammo for one runs out, starshells included in GW.
Unfortunatly i dont know of a way of slowing down the gun manning process, just as i dont know how to make the game stop auto filling the conning tower with out diving. Not sure either is possible.
Another comment on starshells is i noticed in stock GW the damage attached to them was fairly high, which i thought odd given a starshell is mostly made of phosphorus, and has a parachute attached. No real explosives (phosphorus is an incindiery chemical that reacts to oxigen), and the shell is designed to be light so it stays up longer. So its unlikely to penetrate the side of the ship, it doesnt burn when immersed in water, at most it might set fire to something above deck.