My understanding is that jump landings are usually a low to midspeed issue. That being said, I "think" that the HSC clicker (shock) works in the lower range of the high speed circuit, if that makes any sense. Basically you are correct in your first assumptions, but so is the info in Eric's book. As Jer eluded, all the circuits overlap to a degree, and effect the external adjusters (clickers) range of operation.
Anssi is also correct, you must first be sure that your spring rates and sag settings are correct, then move to clickers, then valving (in that order).
With regards to your forks bottoming, have you tried raising the oil level? This will decrease the air chamber and help firm fork in the last 1/4, or so, of travel. Virtually cost free and works to some degree.
Please, I am no expert, so feel free to correct me if I am wandering.