Areanacross is about as tight and technical as you'll get where lifts are 2:1 and landings aren't forgiving. Generally outdoor faces are 3:1 (not as pitched) and most landings are rolled somewhat (won't hurt as much when cased). Outdoors once built weather and become even "safer", Arenacross is groomed to keep the track condition.
150rguy... don't be surprised if you can't keep you leg(s) from shaking, the other 40 guy's are feeling the same. Your lucky, you'll experience something many that weekend will only get to watch. Beginner class is about as tough as it gets... point being; obviously most will lack the experience which leads to a lot of banging around... remember no one (almost no one) will play tag with you intentionally so keep your temper in check. +++ Thank god or someone of your choice everytime you finish on the bike and walk back to the pits.
In so far as starts, watch a few of the earlier races... you may find that letting the bulk of the riders shoot the hole serves to swing them right (outside) leaving an opening on the inside of the left turn. Sometimes it works sometimes it doesn't... do it this way at least you'll make the turn without being taken out.
On amature day the faces and landing are ground so don't be intimidated by the track on Friday or Saturday. Stay on your seat the entire race and you'll pick up 3-4 positions, ride smart and pick lines carefully... another 1-2 positions. You'll get at least two moto's... have fun. Do yourself a favor, don't brag, or tell everyone I'm gonna jump this and do that... it's only more pressure.
Good Luck...