Yay!! I love your enthusiasm!!
I just got my new tires last night (my stock set was worn out), and will do my first cross race in a week and a half - I imagine I'd be one of those people frustrating you in the race as a newbie I have raced before, tri and mtb, just not CX, and I usually scope out the competition to see where I should position myself - lots of people better than me, I go towards the back; lots of people looking like they're going to bother me, I go to the front. I'm sure you would hate me if I started in front of you, but I'd rather be a bother than be bothered in a race!! hehe - seriously, I do try to position myself behind the better racers at a start whenever I'm in a first time situation. I think it's respectful, I want them to enjoy a good race, as well as enjoy myself with out a bunch of skilled people riding up my a$$
Good luck this season, and wish me luck on the 26th!