A hard roll on takeoff is usually a tip stall caused taking off too soon or too steeply.
As for your question about the stab, most planes fly properly with some positive decalage. That means the wing's leading edge is up a bit if the stab is level. Some downthrust is nornally required in that setup as well. Twist in the wing and tail are generally a bad thing, but many designs can tolerate it. If your wingtips are twisted up in front, that would make tip stalls more likely.