Deceiver_0: My concern about the shuttle is essentially that once the shuttle's gone, what's to stop you creating a new one?
Now, as a graphic effect for a building-based ability, no sweat. The Admiral buff lasts as long as a) the capital ship is alive,
the Strategic Command center remains intact. When you fire the buff, a little ship flies off towards the capital ship in question, who then gains Admiral status (which includes a pretty little icon overhead so you can tell it apart). He can then fly off to do Great And Exciting Things.
Well, assuming there's no annoying catch like phase space shutting down all activated abilities... but let's just hope not on that one for the moment. 