^^^ LOL! You need to join a car club, man! You got a lot of questions that could simply be answered by hanging out with experienced car guys!
Synthetic Oil life is about 5K-6K miles. On some cars it's closer to 10K. If you race a lot, then you
should change it every 1K miles although I know a lot of people that go until 3K. However, even light street racing wouldn't constitute changing it that early. People who run their cars at the track, hot lap, and/or frequent 120+MPH should change their oil often.
I used to race a STOCK LS1 car and won against many modded cars because I replaced the oil after EVERY night of racing.
There is a method to the madness.