Welcome to the forum. I don't have direct answers to your questions, however I would highly recommend that you come out to our autocross/solo events. You don't need to compete to attend. You can walk around the paddock area, check out the cars that are competing, and talk to the drivers. Our members are more than willing to share what they can about setting up their car (mechanics), the equipment they are using (tuning), and the approximate cost. Here's a link to our solo event calendar http://detroit-scca.org/e107/page.php?11
And if your intent is to get driving experience in solo events with your ultimate goal to road race, then you may want to visit with the drivers at a local race track, Waterford Hills. Here's a link to their website where you'll be able to view their schedule. http://www.waterfordhills.com/
We have a number of young members in our region. I can't estimate how many of them compete in the numerous and varied events that we provide throughout the season, but they are more than welcome at any of our events.
We hope to see you at the events,
Steve Road racing is a lot like life, providing curves and a lot of ups and downs to master. Oval racing only keeps you going in circles.