Friday is a good day to show... you can set up camp, look at cars in the inspection line and pits. Saturday morning will be the drivers meeting... always worth attending and you will learn needed and required info.
If you plan to attend the big car show or do anything in town you better bring a street legal vehicle. You can get from the bend to the races without a street legal vehicle, but not to town.
You will need to buy entry passes... I'd suggest joining the BNI, it gets you a gate pass, rule book, poster, patch and I'm sure other stuff I've forgotten