Next question would be: even if you Outwit Indomitable and Battle Fury, if you try to Incap. him, does the Incap. roll need to be doubles for it to apply?

LIMITLESS RAGE: Hulk can use Toughness. Hulk ignores all damage dealt to him unless it is dealt by an attack and the attack roll is doubles, but not a critical miss. Friendly characters cannot use Probability Control during an attack that targets Hulk. This power can't be countered or ignored.

No. He is only dealt damage from an attack roll of doubles, but Incap is a no damage attack. The damage he would take would come from the placing of the second token, which results to pushing damage, which can't be ignored unless specifically said so, so the Hulk doesn't ignore it and gets KOd.