To do rallycross, all you need is an ordinary drivers license.  No special rally license is needed.
An old beat up Audi is an excellent car to rallycross in, especially for a beginer.  It doesn't need to be street legal, it just needs a few safety things.  They will check seatbelts, and make sure the battery is secured, and some other minor things like that.
I don't think it's too late to register... considering that they haven't even made an official announcement about the series yet...  Once they've done that, you can register online, or if there's still spaces left, you can register at an event.
It's a good idea to come out to a meeting anyway.  You can talk directly to people who know this stuff, and get all your questions answered.