Natural balance is a real good food, I fostered a bulldog(english) and natural balance was the only thing that kept under control.
I feed my bulldog blue buffalo, never had any problems.
As far as snacks, you can give carrots, green beans, apples will give your dog energy but don't give them the seeds or stems. Natural balance comes in a roll (kinda like salami) wich is nice to cut up for training.
My dog trains on average 3-4 days a week I have to keep her interested so her treats include, cheese, meatballs, tuna brownies, liver, the center bun of a big mac, hotdog, chicken, french fries, and cherrios and kibble thrown in the mix. She is on supplements, and only gets 1/2 c of food twice a day.