You get hit at least once, sometimes twice before being able to hide and then you have to kill it with recoils when it gets low, if the gnomes kill it it won't give you the kill, it will heal.. I'd recommend 30+ HP because the boss can hit that.
Minimum of 31 hp if you're going to be 1 prayer at the time of completion if you don't want it too be incredibly frustrating. Other than that it doesn't matter in the slightest what your other stats are.
11k attack experience will not get you over 60 attack from 40 attack. It shouldn't get you anywhere close . You can actually get 57 attack and do tree gnome village, grand tree and claim the monkey madness experience and not get over 60 attack.