STP is taking himself way too seriously.
Bottom line is that becuase CX is intense but relatively short, there is greater danger in having too much in your stomach than there is in having too little. If you are up early enough to eat at least 3 hours before start time, above advice is solid - eat a relatively full meal, but stick to foods you are familiar with and are reasonably easy to digest. I am a meathead, but not before a race - it stays in the stomach too long. If your start is too early for that, a bagel or something similar will probably do the trick. Either way, energy drink while warming up will make sure you have the short term energy you need.
As for warming up, most everyone agrees more of it is better. I warm up more for 'cross than for any other type of racing I've done (bike, running, whatever). You need to be primed to go from the start. I like to show up about 1:15 hours before the gun - get registered, get changed, get the bike ready, and then start rolling. I'd probably leave a little more for my first race, though.
Mostly, it's your first race - get there eary enough to relax, check out the scene, spend some time on the course (if allowed), and have a good time.
Good luck!