Solo 1
It usually costs 80$ per day to lap plus the membership (once a yeayr, around 35$), which is one of the cheapest timed track events in North America (shop around if you don`t believe me). I believe that the license is 25$, it`s not us who deliver it, but Federation Autp Quebec.
90% of our members track their daily drivers, it's not rare at all. As for tires, you can use street tires, as many members do. They will wear a little faster. Apart from that, your brake pads will wear faster. If the car is in good mechanical shape, there are not that many wear issues. My race Civic is my only car in the summer. People who get addicted usually buy a second set of wheels with better tires and use those only for racing. They usually upgrade the brake pads as well.
As for classification, it goes by stock power to weight ratio, then byu the number and type of mods.