FlapsOne, could you give a more detailed explanation of the negative weathercock effect and describe what causes it?
As far as the critical engine's concerned, it's all a matter of which definition you use:
1. the critical engine is the engine that causes the greatest yawing moment when it fails (works for any multi-engine airplane).
2. the critical engine is the engine which has its centre of thrust furthest from the longitudinal axis (works for props only).
I'd vore for the first definition, as a strong crosswind can easily overcome the effect of the centre of thrust being further away from the longitudinal axis.
Erik.