Hello and welcome,
I have a 12 week furbabe named Couture and she does the same thing. I would say picking her up as soon as she squats and placing her on her pad does work. When she starts to mark I would say bad potty then place her on her pad and I would reply with good potty. It will take sometime to train but if it gets anymore difficult I would invest in some Little Jacs/ Bill Jac treats. There made of chicken liver heres a link
tp://www.petco.com/product/104712/Bil-Jac-Little-Jacs-Liver-Treats.aspx?cm_mmc=CSEMGooglebase-_-Dog-_-Bil-Jac-_-1137867&mr:trackingCode=BE731416-8381-DE11-B7F3-0019B9C043EB&mr:referralID=NA
Now for the biting I've done this with my bichpoo and now my yorkie, this really works! When Debit was with his litter mates they would roll around and bite each other but buy the time you recieved him he did not devolpe the skill not to bite because it hurts. So what I've done is so simple. Speak dog, when dogs are hurt or sad what do they do? they wimper with a sharp cry. That could wake you up in the middle of the night. So the next time he he wants to theeth on you or your furniture just do a lite wimper. I know it sounds silly but I've only had Couture for two weeks and Im seeing results. After I wimper she walks to me and licks me and I reply with good girl, I would then give her a cow hoof since this is what she's allowed to chew on.
Cold Spot Feeds, Inc. Here is a place that sells them for cheap. Now its important that you let him come to you and let him get your hand in his mouth and let him bite a little, and then you can try this trick I say this because you want him to get use to having your fingers in his mouth for brushing teeth purpose. I hope all this helps!