As you noted, the averages could be all over the place depending on who shows up, but you'll see at least 18avg and maybe as high as 24mph avg. But for :30 is an all-out effort start to finish, with lots of attacks. And if your goal is to come out with an intact colar bone, try to hang with each attack and stay in front. Oh, and good for you for getting into crits.

Edit: I just searched and found your race - http://www.hpblast.com - it looks awesome! And it is obviously not your generic Wednesday night office park crit (which I thought it was). As such, I bet your Cat IVs blow the doors of your division and hold a 40k avg. Have fun and hang on! It's probably going to feel like running a 5k where every single entrant can go sub:20. Bring your trainer and warm-up by your car. You need to be fully juiced before you start.

It will be a standing start, and attacks will come as soon as the first person gets clipped in. Be prepared to sprint from the start.

Depends on how tight the 180 is and how steep the hill, but looking at the 1/4 mile drag strip in the middle, you'll probably see averages in the 23-25 mph range, with speeds topping out at 35 on the straights.

The bell lap will probably come around 28 (+/- 1) min into the race since it doesn't say 30 min + 1 (i.e. 30 min, plus the bell lap).

1) I'm sure you know this, but you have to be on a road bike and your jersey must cover your shoulders.
2) Keep your gearing lower and spin a higher cadence. It'll help you get up to speed faster coming out of corners and stay with the accelerations and attacks of the group. Be prepared to average 10 rpm higher than what you would do in a Tri/TT with a HR 10-15 BPM higher.
3) Stay in the top 1/3, that way if you do fall back slightly, you're still sheltered in the pack.
4) If you have a chance, get out and ride a few laps on the course before your race, increasing speeds around the corners each lap until you know how fast you can take them. Then be prepared to have people taking them too fast, cutting you off on the inside or flying out wide on the outside. In a 4/5, this will happen at pretty much every corner, and is why you want to stay near the front.
5) Be prepared for your team tactics to get thrown out the window quickly if you haven't been riding together a lot. But it's nice to know that you have people to help out even as an indie. I've been racing all year as an unattached and it's a bit of a struggle when you're stuck behind a team blocking for one of their guys in a break, or you want to bridge and have to go it alone. My last crit, I spent 5 laps stuck behind a 5 man blob because they had a guy in a 3-man break 50 m ahead and wanted it to stick. I finally got around and tried to bridge, but only managed to pull along the group for 4 mi at 27 mph before I was gassed and got passed by a pack of 10 on the backstretch of the final lap with only 500m to go and finished around 15th, sitting up to avoid the pack sprint for 4th-15th.