The other thing I never quite got was the idea of extensor action when swinging. I understood it but couldn't incorporate it very well - it just felt too "tight". For me there seems to be a tie-in back to the frozen RW that I'd been missing. With a greater focus on the frozen RW, the application of EA makes more sense. Not saying I have it down, but I've finally been able to make some swings with EA engaged and I can see why HK felt it to be so important. Being able to use EA with more/all of my swings is becoming a new goal for me.
how important is the frozen level right wrist? It seems to be very important to me.
When the correct Start Up and Backstroke motion is employed, there is no inclination to cock the Right Wrist. Hence, it remains Level.
As an analogy, a wrist in a cast is "frozen" in its condition, but it may nevertheless be unstressed (and not in a tensed, rigid state). This is the way it is in the Golf Stroke.