I"m guessing NSTU stands for Novice Street Touring U autocross? Like others have said, probably not the best choices; but honestly, as a novice, it's 90% driver and 10% car, so don't worry about it. Do the Pedders come with camber plates for the front struts? If so, try to get -2 to -2.5 degress front camber so as the car rolls in a turn the outside (loaded) tire stands up straighter - it will reduce chewing up the outside shoulders of the tires in turns.
If you haven't gotten the tires yet, I'd go with 265/35 or even squeeze a 275/35 on the front, to better balance the 285's on the rear. With the 255's on the front, I'm afraid the car will have too much understeer to drive aggressively and learn quickly. As opposed to most others here, I'm a big fan of learning car control on cheap, crappy tires. They won't cover up bad habits with too much grip, and you'll develop smooth inputs from the start, which will help you in all motorsports in the future. After a solid year or two when you burn through the cheap tires, then step up to the grippy rubber.
Like I said above, starting out it's 90% driver, and autocross is very much a mental game, so do your course walks until you can draw the course from memory. Take instructors whenever you can, and ask experienced drivers for ride-alongs. Don't be afraid to ask questions - autocrossers are friendly and we want to encourage novices to come back.
Most importantly, have fun!