[Radek]

1. I am not sure whether the hammer mentioned by The Relic will do. If I understand well, the "giant kin" means Ettins and similar races but not golems. I don't know. I tried the hammer only shortly and then I sold it.
2. I was never able to hit Iron or Adamantine Golem with something worse than +3. Perhaps, the golems in Suldanesellar can be hit but they are really weak compared with the golems you will meet earlier in the game.
3. Fighting Iron and Adamantine golems. You'd better attack them from a distance. They are huge so that they always hang in doors or narrow corridors. Let them hang, catch your ranged weapons and attack from a safe distance. You will need +3 ranged weapons. Available +3 ranged weapons in the game: Tansheron Bow, Sling of Everard, Rifthome Axe, Azuredge, darts from Cloak of Stars, and IIRC, some throwing daggers. Also, Mordekainen Swords are +4.