3, 5, 7 and 8 are more down to personal prefernce IMO, but all in all a good set of general things to watch out for.
Oh, and about hitting slippery roots at 90*, I generally find as long as I can get my front wheel up them, genrally by just pulling it over, I get can my rear up as well, even if it does slide along a bit. Not always possibly to hit them square on so it may be useful for people to practice.
Last edited by Dheorl; 06-03-09 at 02:58 PM.