Puppies do bite and chew. That is all normal. Your puppy is very young and won't be an adult for some time, so brace yourself. LOL.
Bring your pup in from outside and pop him in his crate. (I'm assuming you're crate training) Ten minutes later, take him back outside to try again. If he still doesn't, pop him back in his crate. (crate should not be bigger than is necessary for him to stretch out when lying down, stand up, turn around) It is unusal for a dog to mess up his den. Finally, when he goes outside, give a command word, "go potty" (whatever) while he's going and the second he's finished, praise like crazy and give him a treat. Then bring him in and play with him. It also helps to write down when and what you feed him, when he drinks, when he goes to the bathroom. That way you learn the times he's likely to go, so you can eliminate unnecessary trips outside. It will be a hassle at first because you have to keep taking him back outside and putting him back in his crate, back outside etc....but if you're diligent, he'll learn. He has to be watched literally every second while loose in the house. He must be prevented from going to the bathroom inside. The more he does that, the more that is reinforced. Don't scold him if he does. It's not his fault. Just watch him very closely or put him in his crate when you can't watch him.
The biting when he's playing is normal. He is probably getting a payoff for it. (attention...good or bad) When he bites and it hurts, walk away, end all playtime. Give him something he is allowed to chew on and praise him if he chews on that. When he does play nicely without biting, give him a little treat and some low key, gentle voice praise.
Read the sticky about stages of puppies. (what to expect) That way you'll know what's normal and what you have to look forward to. LOL.
