I don't know what kind of dog food you are feeding him, but that doesn't sound like enough at all! Puppies eat more than adult dogs. Here are the feeding instructions for Canidae All Life Stages:
http://www.canidae.com/dogs/all_life_stages/dry.html
It is at least a reference to show how much more puppies eat. Please double check that quantity.
Also, there are great guidelines on here for puppy training and if you google puppy training, you will find even more. Behavioral training, which distracts from bad behavior and reinforces good instead of punishing, is fantastic! (and really the only option IMO)
Potty training is pretty easy if you use the method consistently. I also recommend walking him out to the same spot every time and saying "potty" or "hurry". Pick a word and use it every time. (That will also help teach them to go on command, which is great for trips when you want them to go quickly while you stop for gas.) Then while he's going, softly say (so he's not distracted), Good Potty or good hurry a few times, so that he's knows he is in fact doing what you wanted. And then like Groupie said, give a treat right away.