Quite simply, I know you're able to acquire new bridge officers at various ranks within the game. I'm at 46 now and have acquired a fair few of them myself. Most of which have since been sold on the Exchange.
What I am interested to know (because I now wish that I hadn't sold them all) is where I can acquire new ones, specifically the very rare kind... What story-based missions can I acquire new bridge officers from? -- I know only of the Doomsday Device thus far; last weekend I completed the Romulan campaign, and I know there are none there.
In addition to that, what areas are there that I can travel too and have a duty officer assignment provide me with a new bridge officer. I know they're out there, I've had the option before (I restarted the game) - I know also that Klingon's can get Letheans this way. I'm a Federation player at the moment, and wish to build up my Federation crew.