And I'll agree with AntonK here - next time you're in a balanced 45degree turn, look down the wing.. Spiral dives exist because the pitch effect is markedly stronger than the roll stability.
As for stalling in a turn, I find it helpful to consider what is admittedly a fairly far fetched boundary condition - imagine the aircraft is climbing vertically in a spiral with the inner wing anchored to a pole - so the inner wing has zero forward speed. The relative airflow is from directly above, inline with the chord of the wing.. Now consider the outer wing - that has a forward component also, so the relative airflow is from somewhat ahead of that chord line - coming from underneath the wing - it could easily be stalled.
Now, if you move it out to more sensible climb angles, and more sensible sizes of circle, the same relative effects remain - if the inner wing is at 0 deg AOA, the outer will be at some +ve AOA; both wings climb at the same rate. Add in the aileron effects too, and it should be clear why the outer wing goes first.