Regarding tires, look in the 215/45/17 size, tons of options there.
For what to use in competeing, try a few times and see how it goes. From there, another set of stock wheels (find them cheap, used) with some sticky tires could be a good place to start.
Parking Lot Hero
2008 WRX daily driver
2003 ZX3 23D Autox Car 42 FSP
"Hella Functional - Raced, Not Hard Parked"