Is Ironhands parry ability based on that skill itself, or does Ironhands use the parry skill aswell?

With hand-to-hand combat in general, what does your base damage (as far as dice go) base itself on? Str? Weight? Level? etc?

To parry you need to roll a succesful ironhands and a succesful parry. Damage avg is contigent mostly upon level with some variables I'll leave you to figure out on your own.