Medium and no dumpoff is what we usually use. Depends on the catching ability of the HB though, but I think medium passing should be what the majority of teams should be going with.
Depends on the defense. If you're facing some serious ball hawks in the secondary, then go bullet. Otherwise, medium should be fine. I personally like Dump off at sometimes especially if you're facing a quick DLine.
A lot of it depends on your strengths and weaknesses. And the Defense. My WR got some good hands so I can get away with bullet with very few drops. Bullet does wind up with more drops but also less picks. I don't normally dump off but I don't have it completely ruled out either. But then my RBs aren't exactly there to catch passes. If I was running a spread I would probably dump off a lot more. So it all depends really.