In my personal experience, its true that skinny guys have a higher incidence of large endowment. Also, in my personal experience, Jewish men seem to be insanely hung (I have no idea why).
Adam Levine is skinny and Jewish. He is likely doing okay for himself. But you never know. This is all idle speculation, since no one has seen the chap naked. I have know skinnny hairy guys who were pretty teeny.
as for his sexual orientation . . . when his first video came out, I thought, "Man! What is this guy trying to prove?" then I forgot about that and enjoyed the hot sex and references to trying to please his woman. if he is gay/bi, he is really making sure he gives the opposite impression. Or he coudl be like most men who are suddenly put in a rocker status and is relishing the chicks that come wiht the deal.