Chris Scott - you are absolutely correct. Weather-cocking takes place on the GROUND, and drift is simply the angular difference between heading and track. It takes place in the AIR!
On the question of "critical engine" related to a jet, there is no comparison with that of a propeller driven twin. There is however an engine that we would prefer not to fail in some situations, most notably being when taking off in crosswind conditions in a LIGHTLY loaded aircraft.
In such cases (jets) the calculated V1 for a given WAT may actually compute to a speed below the "real" VMCG. The stated Flight Manual VCMG is determined without any consideration given to the effect of crosswind, so the loss of the upwind engine after V1 may, in the case of a lightly loaded aircraft departing in a crosswind, result in a loss of directional control.
The solution? If the TODA permits, increase the V1 by picking a different weight from the tables, but by no more than VR of the actual weight. V2, also should be based on the actual weight.