The one plane swing requires that you bend from the hips more than the two plane swing set up. This move is counter balanced by your buttocks going back more, thus maintaining your balance on the balls of your feet.
To develop a consistent and repeatable swing every club in your bag should have an identical tempo and rhythm, tempo is the rate of speed from start to finish of the swing while rhythm is the acceleration and deceleration of the golf club
For downhill lies reposition your club and body so that your stance is parallel to the slope your ball is on