There is plenty of free parking on race weekend. The northwest, southwest, and northeast parking lots of the State Farm Center are available on race weekend. The E14 lot is also available all weekend, as well as the Research Park south of Oak Street. There is some paid parking closer to the expo site.
You can view the parking map here.
The handicap parking is in the north-most row of the NW lot of the State Farm Center parking lot. You can cross Kirby Avenue at the cross walk. Enter Memorial Stadium at Gate 32. The handicap seating is in the south horseshoe.