Kenly, you pretty much know youre not going to use fresh tires there, so id have tires at least a month old, to 2-3 months. Amount of sets depends on amount of classes ran. Normal racer, 2 classes, could get away with 4-5 sets.
El tires, 2 sets for the normal racer.
3sets will probably do. That's a RF, RR, LR. Get a LF that gives you the front stagger you want and just leave it. Carry a spare LF in case you cut a tire.
Prep the 3sets to say 42, 45 and 48. The RF and RR need to be 34" in circumference. LR stretched or shrunk to your rear stagger.
You are on a steep learning curve when it comes to tires.