Don't be afraid to only run 2-3 classes per weekend. That's a great way to gain experience and last a little longer in the sport. Over the years I've seen a LOT of people come and go through the sport, and watching an amateur run 5+ classes per weekend, every weekend was almost a certain kiss of death.
All depends on what you want to do. If it's have fun, I'd recommend a GT race on Sat and a couple sprints on Sun and that's it. If you want a championship and can afford the incredible associated expenses, do what you need to.