Step on the ball is a new one on me, the rudder application would be too late by the time the ball has moved to give a coordinated turn, the way I used to instruct it was as you move the stick get the knee out of the way.

Adverse Yaw is caused by the down going aileron causing more drag than the up going aileron therefore the nose goes in the opposite direction to the turn and needs rudder to coordinate the turn correctly.

Mike