We are dealing with the mouthing issue at the moment. T is also loosing puppy teeth although after checking this moring I think they're all gone, even the retained canine that I was starting to think was going to be a problem.
I am doing the same - yelping and ending the behaviour and this seems to be working. T does it as his first greeting after work or if I have been away for anything longer than about 1/2 hour. He jumps up and then grabs my hand on the way down which can be quite painful. Once I yelp he now immediately lets go and his mouthing is getting softer so now it is more of a mouthing rather than a bite or chewing. Thankfully he has also stopped snapping at faces (after doing the same yelping thing) and will happily give me a kiss (lick) and I don't have to worry about having my nose nipped
