Congratulations on your first "hard" race. It will get easier as the season wears on.
Regarding your brakes, I also have a set of Avid canitilevers, and I've found that installing a wider cable yoke helped increase the braking power because you can decrease the yoke angle slightly and thus increase the mechanical advantage. Sheldon Brown has interesting article regarding this
very subject. Also, your brake pads may not be optimal for wet conditions. Although, I have yet to find a set of pads that do all that well in wet conditions. It took a lot of dinking around before I finally got my brakes to perform adequately. I actually don't use them much in a race. It is, however, nice to be able to lock up the rear wheel and skid down a sketchy section of wet grass or mud.
Single chainrings are the way to go, in my opinion, as they simplify the bike, make it easier to clean, and reduce the likelihood of chain derailment, because you can shorten the chain quite a bit to increase tension. With a single chainring set-up, you need a chain guard on each side of the chainring. You can run a "Third Eye" or similar chain keeper on the inside. They work really well when adjusted properly. You could try just using the 36t chainring, with a chainguard, although I think you'd find yourself undergeared. You'll probably need to pick up a 40t or 42t chainring to obtain reasonable gearing.
Eggbeaters and Time ATACs are the standard for cyclocross. I like Time's because of the wider platform and solid reliability, although they don't have the 4-sided entry, like the eggbeaters.
I hope this information is helpful to you.