Lots of questions but it really boils down to your training method.
If he knows "HEAL" then reward him whenever he heals himself. Leash of Learning should also be used if you heal him. Remember to reward him if he heals himself.
Just one thing to remember ..ooooh ....I forgot exactly but something about heal and reward..
Best to find a skirmish land with a heal Miracle Dispenser on it. If you hand your creature the miracle bubble, he'll attempt to cast that miracle. This way, you can more quickly get him to heal himself and you can reward him to do so again in future :: .