Tires balls are commonly referred to as "clag". Clag and asphalt are easily cleaned with kerosene.

Start being more diligent in bleeding the brakes..any brake fluid spillage will eat your paint. Water is the best neutralizer. That being said, if it was break fluid, your paint on your caliper would be soft and stained. If it's not, it's a different fluid.

If you're thinking of replacing your bleeders, research "speedbleeders".

As for things not happening during street/autox but happening during track events.....WELCOME TO THE GAME!