I can't point to rules that explicitly state so, but in my opinion the boss isn't a "mech". I mean, it is a mech, but not a "player mech", which is what "mech" typically means in the rules.
1) Don't heal the player mech, since it is the boss pushing, not a player mech. The game doesn't need to be easier anyways and the intended point is that you use a wrench to heal a partner, the boss isn't your partner.
2) It damages the boss, but you can't hit additional minions behind him, otherwise only scythe would be able to blue damage to the boss and this doesn't make much sense since ripsaw is an attack card.
This is correct.