Your puppy is still so young--give him a little time to learn the ropes! If you are really concerned though, you should take him to the vet just to rule out a bladder infection or other medical reason for him not being able to 'hold it'. In the meantime, keep taking him out every few hours and make him stay out at least 15 min. to be sure he's all finished, and keep up the praising. When in the house watch him carefully and as soon as you see him walking in circles and sniffing the floor, get him outside! It usually doesn't take more than a week or two to train a puppy, but he could be a little slower or just not be familiar enough with your home to know where to go. Crating usually works well, but I know lots of people who don't like locking their dogs in crate all day. You just have to be very consistent, give lots of praise, and really clean the areas where he's already had accidents so he doesn't smell it and think thats the place to go....About nipping--that's a very normal puppy behavior and shouldn't be punished but definitely needs to be corrected. Be sure to give him lots of chew toys and when he goes to bite a person, tell him 'no bite!' and hold his mouth closed. Then offer him a toy and say 'chew this toy' and praise him for taking it. Again, lots of consistency and once he's older get him into obedience class.
Good luck and enjoy your new puppy!