I'm trying not to laugh, but I so know the mouthy behavior. I had Rotties and Chows mostly, and a puppy biting ALWAYS responded to a squeak and no bite. I got my first Basenji and if I did what most trainers say, a high pitch squeak and "no bite"... SHE BIT MORE. It was like I was a squeaky toy. I called the breeder who laughed her butt off. In fact I may have posted about it here too. Sigh.
One issue may be that they learn better bite inhibition from litter mates. At 8 wks, sometimes it's too early to have gotten the message... so now you have the chore. My advice is to stop immediately all play and ignore the second the teeth touch you. Say NO BITE loudly and turn away. Mary's site has training on sit/stay and Leave it. At least read through them. You need to consistently put back into a sit, no treats. Some dogs are SO food oriented that you have to stop using treats. One of my rotties got so excited if you had treats he went deaf (and you could see the whites of his eyes!). I switched to a clicker with him... first doing simply things, eliminating all treats pretty quick, and then none. None of my other dogs have been that insane about food (though I had a chow who, when she wanted a treat, would do her whole repertoire of tricks in quick succession and just didn't get that she got treats ONLY if I gave a command and she did it, not if she initiated).
I am sure others here will have great suggestions. But this should get you started.
This is great (Mary's site has training for most areas and she is simply superb)... but skip the yelp, say "NO BITE"
http://www.clickerlessons.com/puppybiting.htm
As for the rest, her last line says it all... a tired puppy is a good puppy. Much more play/walking/exercise will help with most behaviors.
On the lunging.. try it at home once or twice a day.. put him in a sit, TREAT before release. On release, "good dog!" is the reward.