Forget Cesar Milan if you are using him as a resource to raise your puppy. The methods he teaches can be very harmful to your dog and you can easily cause a lot of problems using his "theories". As far as rolling the puppy on its back, it's called an "Alpha Roll" and is NOT something you do with a dog, much less a baby. (
http://k9domain.org/alpha_theory.aspx)
In short, dogs don't understand what an Alpha Roll is or why they are being forced on their back. Puppies need to learn to trust you, not fear you because you might roll them and hold them down. Not fun. You want to teach the dog to be calm so you need to reward calm behavior. Not punish him for being a puppy and being excited.
As far as walking, are you walking on grass or cement? Generally with puppies you want to be careful with their joints. You don't want to walk on cement/asphalt for long. You don't want forced exercise (running/walking) for long periods of time because this can hurt their joints. I would get a long line or, since he is a smaller dog, some twine that is 20-30 ft and take him out to an open grass field. Take some really good treats and let him explore. Just kind of follow him and walk around, let him explore. If he comes up to you, say "good job!" and give him a delicious treat. This gets all his senses working as he explores around and gets him to start thinking that if he stays near you he gets delicious treats.
Do more, smaller training sessions using positive reinforcement or clicker training. Dogs love clicker training. Puppies are not as able to focus for as long though, so just keep the sessions short (2-3 min). (
http://www.youtube.com/watch?v=_wv1uvvqaSw - She has a lot of really great videos)
How are you training? You don't want to use corrections with a puppy, ever. They are babies and need to learn by you showing them and rewarding them. Training using corrections can just make your puppy not trust you and become afraid of you.