You will most likely have problems with him peeing and being dominant because he wasn't neutered until over the age of three. I have the same problems with Roscoe, since he was neutered when he was about 3 1/2 years old. We put him in an obediance class, which worked wonders. Our trainer said that a dog neutered after the age of three is still considered 'intact,' at least in his mind, which means that he thinks he's the leader of the pack. Have you ever put him in any obedience training? If not, would you be able to? If you can, I highly recommend it, the class saved my sanity

EDIT: I had another idea, they have those 'pee posts' at petsmart that you can put in your yard that is supposed to draw the dog to it to pee on - that might help if he's doing this outside. I can't find the link for it, but it's a yellow post that you stink in the ground.