This week is Dog Whisperer week on the National Geographic Channel. He deals with these situations all the time. Try to wach some of his shows.
It really sounds like your dog does not respect you as top dog. You have to establish that position before you can correct any of his behavior.
Check out Cesar Milans website for tips on how to establish yourself as Top Dog.
http://www.dogchannel.com/experts/cesar/default.aspx