never,ever let your dog bite you even when he is playing. I do one of two things. I either close the dog's mouth and say no bite, or I give him a quick slap upward on the bottom of his chin( not hard). Repeating this will reinforce this everytime he does this.
Forget the tug of war game, it can come to no good.
This is a doiminance thing as well and he must know you are doiminant and the leader of the pack so to speak.
Any unwanted touch on his part without you iniating it should be discouraged. You set the rules and stick by them. You are the dominant dog to him.