Hi Blair,
I've heard, or seen, several people that have had issues with starting smoothly. As you only have about 2 hours in your car, I think that is just going to be a practice (seat time) issue. Perhaps you can find a large parking lot to practice your starts. The throttle pedal and clutch can be pretty touchy on these cars. You may need to change the pivot point on your throttle pedal to get a better response and feel from the pedal.
You may also need to adjust your clutch pedal as well. Remember to immediately push in the clutch if you spin. Getting backwards while in gear can cause some serious damage to your starter chain.
I have seen many cars with knee protectors (knee guards). You can make or purchase them. Speedway Motors and many other race part dealers sell them. Or you can fab up your own.
Again, I am going to say that Seat Time is going to improve your driving skills. These cars are very twitchy (quick to respond). Not like driving a street vehicle. Everything happens a lot faster! Several things could be causing you to spin... Wrong chassis set up, bad corner entry and/or exit (driving line), braking and throttle points throughout the turns, etc..... Get all the practice time you can!!! Perhaps find a race driver or team that you can work with to help you improve your driving skills. Study the faster drivers at your track. Watch videos from any of the races you can find online at your track. Make note of where they brake, turn, accelerate. Perhaps follow a faster driver through some practice laps (as best you can) and learn how they are getting around the course. I know it is not an easy thing to learn; But follow the driver ahead of you and think about how you can make the next lap better. Don't know if you are a lone wolf or have a crew to help you out. Have a friend or family member video your runs. Or even get a video camera and mount on your your car so you can study your strengths and weakness around the track. All this doesn't cost a bunch; It's just a bit time consuming. What you will learn is priceless!
Steve