Falcon-
You've got a lot of questions there. In the future if your questions are somewhat unrelated start different threads so that it's easier for people to find what they want by looking at the title of the thread.
As for your quads, I think it's just a strength issue. The primary difference between sprinting and distance running is that sprinting involves much higher power and force outputs than distance running. This means if you're not accustomed to sprinting you'd get sore much in the same way you'd get sore if you were doing heavy squats for the first time.
ELITETRACK Founder