While this swing thought can work, I think it actually is at odds with the Skill 2 that you listed. If the impact is at the edge of a perfect arc, the club should be working around the body and not intentionally down. If you are swinging down through the ball to hit a leaf (or a tee or anything else in front of it) then the club is no longer moving on a perfect arc -- there is a flat spot in the club's path. Like I said, this method can work -- it tends to work much better for two-plane up-and-down Nicklaus-type swings -- but I think that it is at odds with the goals of Skill 2.

The downward blow of the club comes from a good setup position -- specifically the spine angle and maintaining that spine angle throughout the entire swing.

And, skill 3 I feel shouldn't be a conscious feeling. It is a timing move if done deliberately. The natural movements of the body will bring the club from open to closed completely as part of the club's own inertia and the physiology of the human body. Now, again, there is power in this closing movement -- anyone who has used a screwdriver knows that -- but I think that holding off on closing in order to time it at just the moment of impact can lead to very inconsistent results. Especially if you aren't able to devote almost every single day to practice.