Nascar is discretely termed a car contact sport down here, little bit of nudging here and there. Great racing though. To get into it,I I would suggest getting in contact with the local dirt track club, and checking out the rules and regulations. Racing a car is a team effort you have the driver of course, but then you have the people swinging the spanners and driving the pusher/tow vehicle. Dont be put of by the comments "but your a girl". Your keen to do it, go out and show them. From what I have read and the photos I have seen of you, you afe a very unique girl who has heaps of personality and is definitely not an airhead and I have a suspicion that you dont sit around to see what happens, you make things happen.
Here in New Zealand we start of with C class which is basicly stock motor and none welded diff, and experience and money invested takes off from there. As I mentioned above The US dirt track clubs will have their own rules but they should'nt be all that different from ours because we copy nearly all of them anyway!