noob HPDE questions

chillz

I just got the Z a month ago and I'd like to do an HPDE1 session. I searched, but I still have a couple questions:

Lime Rock (March 31st) and NJMP (April 21st and 22nd) are both within driving distance for me; is one track preferred for this event over the other, and is there an advantage to the two day event? This would be my first time on a track.

I've read in threads here and on the NASA forums that it's best to keep one's car stock for the first few events (assuming I did more than one). I also have no idea if I'll ever do this again, so I'd prefer to spend as little money as possible on stuff I might never need again. Having said that, I want to be safe, and to have a good time. Is it necessary to change the brake pads for the day, and will I need an oil cooler, especially if I did the event at Lime Rock, which is in late March?