RSX is running 16inch rims with all season tires right? 16inchs is the standard, if you go any bigger you will be losing grip. Now tires has to be Z rated for the best performance wise and speed handling, then the sticky the better. I don't quite remember the stock tire pressure of the tires, you want to run 2 psi lower on a hot day and rise it 2 psi on a cold day to account for the pressure expansion etc. But those numbers are not the standard, you have to get what you feel most comfortable driving. Don't lower it too much then your tires will be taking some damage. The brands are different, Yokohama, kumo, mitchellan, pirellis whats most common. There is a new brand that actually doing very well, and its quite cheap, its called NEXEN, its Korean. If you want to go to the track a couple of times in the summer, I suggest getting another set of rims, either to upgrade the looks of your car and run stocks for track or get a set to run track. If you want some I can find you some cheap ones or look through usedottawa.com and there might be some good ones.
As for the brakes, you are running stock now, and you said CAI and Cat-back, ECU later on and some other little things. If your car comes close to 250hp at the wheels, I would say upgrade the brakes. You don't need a big brake kit if you don't want to, its really expensive. Just get cross drilled and slotted rotors and I think that would be enough, thats what I plan on running cause I don't feel like paying over $1500 for new brakes.