I know a good way to teach roll over but I dont know if I'll be able to explain it well typing it. I tried it with Harley and he did it the very first time.

Grab a handful of good treats cut into small pieces. Have the dog in a down position and rolled on to one of his haunches (either side). Hold the treats in front of his nose, he can lick and nibble a little on them. Holding your hand still in front of his nose, guide his head to his side in a tight circle type thing, sort of around the head. As he turns his head for the treats, he'll naturally roll over. If he does, give him the treats and praise.

Eek, I just read this and I see I can't explain it at all without demonstrating. Maybe you're a psychic and know what I'm saying though