I think hawk's advice is generally good, but it's not the advice I would give YOU.
You're not going to be in the running to win the meet, so have some fun! I would totally watch the meet, and enjoy the camaraderie. Meets are a cool place to meet people stronger than you, and learn from them. If you sit by yourself with your IPod, I think you'll really be missing out on a good time. Hell, I don't even do that. It's not necessary. I don't get into the zone until the last couple minutes before each lift.
Be well rested leading up to the meet, and trust the process. I take an entire week off leading up to the meet. Then the day before the meet, I'll do a few reps of each lift with just the barbell, just to feel the movements one last time. Taking this much time off makes me feel like I'm going to be weak on the platform, but this has never proven to be the case.
Pre-meet, you should have your first attempts set. A good rule of thumb is to pick a weight that you can triple on a good day, and that there is absolutely zero chance you'll miss. From there, I sort of play it by ear, but my second attempt is usually going to be just under my best gym lift, assuming I've hit a 1rm fairly recently. Last attempt is usually a PR. I'm flexible though. If my first attempt is a grinder for some reason, I'll back off on my 2nd attempt to something a little less than I had planned.
I like to get my calories throughout the day mostly in liquid form, but this is a personal preference. Do whatever works for you.
Don't overstimulate yourself. Do whatever you do in a hard training session. If you usually use stims, caffeine, etc, use them. If you don't use them in training, you probably don't want to use them in the meet. Familiarity is your friend.
One of the biggest mistakes I see among young lifters is that they do a zillion warmup reps. They're doing sets of 5-10. like they're trying to get a workout in. Minimize your warm up as much as possible. I'll use your squat as an example. Let's say you're going to open with 285. Take the bar for a ride for 3-5 reps. Do 135 for 3 reps. 185 for a single. 225 for a single. And then 255 for a single. That's it. Less than 10 total warm up reps.
Anyway, best of luck, I'm sure you'll have a great time, and hopefully hit some PR's!!!