MM + Mystic Vigor, etc.

If I have Mystic Vigor, or another enchantment which heals each time I hit with an attack, on a Minion Master, are they healed each time one of their minions attacks?

No, because the MM doesn't hit himself.

There is the key

your minions are hitting not you so no.

There are some nifty little builds for a N/D that are quite popular in Alliance Battles. Self-heal is important because everyone goes after the minion master, and the derv heals really fit the bill.