Good start , now you just need to get a set of rims and some sticky rubber to become a quick cone carver. Top three 200 Treadwear Rated rubber for racers at the Solo Nationals were:
1. Bridgestone RE71Rs
2. BFG Rival S 1.5
3. Yokohama A052
Many of us have used the Apex rims for a square set up, but check the rules for the size you can use depending on the class you intend to run in ------SCCA has the largest Club for Autocrossing, whereas NASA will have quite a few more HPDE events in most of the US.
I would definitely go with the 18x11 Apex rims , as many of us learned the hard way over the last 4-5 years that the 10s were not the way to go. You can get a 315/18 Hoosier A7/R7 or BFG gforce R1S and both are tremendously faster than the ancient NT01. You also have the option of getting used Michelin or Pirelli race slicks , which many are using if doing just HPDEs. Depending on your class Autocrossing, you possibly use the 18x11s with some big 200 TRW rubber ( 315s are out there )- say if you are running in the CAM class?
Ever been to the Solo Nartionals as I started auto crossing in the early 80s .....and plenty of time in Mazdas, Hondas, and the like over the years.