Mainly grass and gravel tracks. Some climbing - usually a couple of sustained climbs a lap, but a few more short hauls too.
Everyone's listed many of the good things. Make sure there's a fiver in your Camelbak for being able to finish a bonky lap and go direct to the food tent to get some grub.
Eat as much food as you can for the entire weekend. Calories are all good in these situations...
Don't take any food or clothing, or gear that'll need thinking about or preparation time.
I put all my socks in one plastic bag, shorts in another, tops in another, and so on - easier when you're brain's broken. And a bin bag for all the dirty stuff.
HSS Hire Shops do a decent range of helpful things. MikeD from BM rented a 6ft battery powered striplight that had enough power to light his camp up for two nights, he also rented a gas powered hot water urn. Having constant hot water makes it so much easier for midnight tea/coffee/noodles...
Assuming you're going to be sleeping, take pillows and duvet from home. You may as well make your two hours as comfy as possible. Take and old towel and bucket for 'instant shower' if you're just freshening up between laps. If you have enough spare shorts, then change them as often as possible.
Most importantly though - make sure that your team mates all have the same race goal in common. If it's just to finish, then there shouldn't be any arguments over someone riding slowly. If you're all out to win, then you can shout. If not, then just enjoy it and remember that at 5am, nothing's funny any more. You'll get through it.