Yeah a lot of good advise in here, i would say only do a couple of laps at a time in a standard road car to stop things overheating especially the brakes, avoid the initial rush right as the track opens first thing then after lunch.
If you get stuck in traffic, just come in and go through the pits, don't get frustrated being behind someone who won't move over. Conversely keep looking in your mirrors and move out of the way in a safe manor on the next straight if someone is clearly faster than you.
Also no matter how fast you think your car is on a track day you'll always be overtaken by someone in a tatty looking Clio going at warp speed, track days are no places for egos about your car but some people have a weird thing about not wanting to be overtaken by 'lesser' cars
Evening or half day sessions are really good especially to start with, i found i enjoyed half days more as it was enough for me. It's very tiring concentrating so hard when driving, it also keeps the costs down as you go through tanks of petrol like nothing and you should still have enough tread on your tyres to make it home. I know my local track (Anglesey) had a club you can join which ran members only evening sessions for 2 hours from 6-8 in the summer which were perfect for me, i could go straight after work and have some dinner in their cafe while listening to the briefing and have a couple of hours of fun. They were also only £20 a session when i started going which was an absolute bargain but i think they latterly went to £50 last i heard.
I never bothered with insurance but my car wasn't worth a fortune and it wasn't my only car so if i did prang it i could get it towed home and fix it on the drive. When you sign on to the track day you normally agree that its every man for himself, so if a pile up happens regardless of who's fault you're only liable for your own car. That is however very different on places like the Nurburgring where people can and do get charged a fortune for damage to the track itself and other cars, but i doubt that was going to be your first port of call anyway as its a very unique place.
You will have an absolute blast though, track days are awesome.