This knowledge comes by way of being a movie and music geek.
1. Nicholas Cage did not appear in Fast Times at Ridgemont High. Well, he did, but he wasn't using the last name "Cage" yet. He's listed in the credits as Nicholas Coppola, a name he later changed to avoid being accused of riding the coattails of his famous director uncle, Francis Ford Coppola.
2. Cage actually did have a speaking part in Fast Times. In the scene where Brad and his buddies are standing in the gym awaiting class assignments, Cage says "Hey Brad. Your sister Stacy is a fox!" That scene got cut, but you can still see it in the cable version of the movie.
3. The Led Zeppelin scene always bothered me. Mike Damone gives Mark Ratner the sage advice to play side two of Led Zeppelin IV to "get the girl in the mood." Notice that when Mark and Stacy are driving to the German Restaurant, he plays "Kashmir". Kashmir isn't on Led Zeppelin IV. It's on Physical Graffiti.
Man, I have watched this movie way too many times.