I cannot offer any expert advice but one thing that I have done since I got Tucker was if during our play he even accidentally nips me, I immediately stop the play. This way he associates a nip with the loss of the play he so enjoys. I'm also very careful not to pull anything from his mouth, by that I mean a toy. We play catch/fetch all the time if he does not drop the object/ball at my feet or in my lap, I do no take it from his mouth. He's never nipped me, and probably needless to say never let him bite on your finger for any reason. On the food issue, I have no advice because I have no experience with this problem. I've taken things from Tucker's mouth if I find him chewing on something and I don't know what it is. Even with a doggy treat, he'd let me take it out of his mouth.
Mum to Tucker, born May 14, 2005