Also some lift is still produced above the stall AoA, so any difference in AoA between the wings will generate some degree of uncommanded roll. Then the down going wing will have an increased AoA (less lift, more drag) due to the relative airflow and the up going wing will have a decreased AoA (more lift, less drag) which will perpetuate the initial asymmetry and set you up for a nice auto-rotation.
Exactly. The difference between the unstalled and stalled regimes is that in the unstalled regime the aircraft is
stable in roll rate (induce a roll with aileron, and the roll rate damps out). In the stalled regime, it's
unstable, for the reasons 500man describes.
Blaming asymmetries between the wings is a little like saying "the ball bearing fell off the point of this pencil because this side of the point is slightly sharper than the other". Strictly speaking, it's true.