Dont worry too much about fast, if in doubt leave it alone at 1.5 turns out. I have my fe570 at 2 turns which is soft and i leave it there. If you go to 1 turn this will increase damping, it relates to compression of spring at high speed.
The slow comp at the top of the spring and reb at the bottom are the clickers you want to be playing with to give the best feel for your riding. Basically find a gnarly little uphill section and set the comp 10 clicks out from standard, then 10 clicks in so you can feel the two worst extremes. Then keep attacking the same section at a set speed, fine tuning until it soaks everything up like its not there. See the DOC for suspension info.
