Hah! I can't argue with you on most of these because I haven't seen the Hobbit movie and could never keep the dwarves straight in the book. :P

Gandalf is definitely a Power. The question is, which Power...? And yes to Elrond and Galadriel (Deagol and Smeagol were wizards once, too.)

I tend to think Bilbo took the Oath when young, but Hobbit wizardry tends to be a quiet helpful sort of wizardry that involves very little gallivanting around and fighting dragons, and besides big showy interventions are for kids who are still overflowing with power, he's already too old for that sort of thing surely!!!