If you are going to do autocross and track nights, I recommend that you get the car aligned to the factory specifications for the V6 1LE car. Those specs are in the high-performance owner's manual supplement. A copy is attached here. If you are new to autocross and track days, I don't think you need to do all the track prep, although I do recommend the early oil change and doing a drain/fill on the rear differential. Some pretty dirty looking gear oil came out of my diff after only 1500 break-in miles.
I recommend against lowering the car and adding wider-than-stock rims. Your 2.0T can be very competitive in the SCCA D Street autocross class, but you will bump into a very tough modified class if you use wider rims or lower the car. Keep it simple and spend your money on track time, tires and proper maintenance.
Also, I am against lowering cars without upgrading the dampers (shocks/struts). You will mostly just compromise the car's ride and feel sportier, but perhaps not have a car that actually handles better.
Going to 19s is an O.K. idea, and if the wheels are lightweight, it will slightly improve your ride, acceleration, braking and acceleration. Running a summer performance tire like the Firestone Indy 500 would provide a lot of added traction, compared to the all-season tires your car has. But I think your best bet is to put a summer performance tire on your OEM rims, get some autocross and track time under your belt, and figure out what you want to do with the car. You might love it as-is, and decide that modifying the car would send it down a path that is expensive, not competitive, and compromises street use too much.
Read this D Street thread, it's authored by the driver who was a national champion in a 2.0T Camaro, and he won by a significant margin.
https://www.camaro6.com/forums/showthread.php?t=477232
Cheers, and keep the rubber side DOWN.