[Uppndownn]

I will stab at the answers.

What part of the pivot makes the club go down?

That would be the press forward coming from the feet through the legs to the hips causing the right shoulder to drop. Note: I mean forward press in the pivot as in press and turn, not any move that starts the swing.

What part of the pivot makes the club go out?
That would be after the initial forward press. The turn of the left hip away from the plane line allowing the right side to move through impact with the club moving out toward the plane line prior to impact.

I am not sure at all about requirements for steep vs. more flat plane, other than setup and player preference I reckon. I am guessing that the flatter plane swinger could set up with the trunk of his body more erect than the steeper plane player, but of course I see players take it back on one plane and then go straight up with the club, a la Tom Watson. Your turn, Bucks.