I think that it's such a specific problem (but kudos to you for posting detailed information the first time
) that people don't have an answer for you. Nope, me either.
In my opinion, the humping is fairly normal (albeit unmannerly) dominant behavior. But your other issues are very specific and I don't have any experience with that. Do you think he is licking the area because of the spots, or do you think his licking the area has caused the spots? I will be watching this thread for other replies though.