Hi! You've gotten great advice from everyone so far! I'm going to add my "two cents" worth, so here goes.

1.) Get your pup to a vet and rule out either cystitis, a urinary tract infection, or a bladder infection. If he has any of these, this will cause a "piddling" problem. Antibiotics take care of things, and you may have to do a temporary food change to help heal things up.
2.) This is from personal experience -- make SURE that you're feeding a premium quality puppy food. Many times, puppies can have developing food allergies, and a food change is in order to either slow down or stop developing allergies. I have one dog here (he's 12+ now), and he developed this problem when he started to really blow out with allergies; that symptom, and a number of other symptoms, were the reason we went off to the vet for a diagnosis.
3.) If you have ruled out the above, you need to get your puppy into puppy classes. Besides a pup learning proper obedience from early on, the classes serve to socialize the puppy and also "socialize" you on how to handle your puppy correctly.
4.) As far as the dominance issue goes, your vet can advise you on the appropriate exercises to perform with your puppy. I do not recommend putting the puppy on his back either; there are much better exercises to take care of the dominance issue. My sister had a Black Lab puppy with a big dominance issue, and her vet showed her the exercises to do with Duffy. She was religious on doing the exercises daily, and Duffy is an extremely well-mannered dog today -- all 100+ pounds of him!
5.) Get him neutered as soon as his testes are "available" for removal! Neutering at an early age goes a long way in controlling temperament problems, and makes for a much healthier adult dog.

Good Luck with your new little guy! I had cockers years ago, had Saint Bernards for a number of years, and now have Beagles. Dogs are all great companions, no matter the breed!