Q1: If something is not all it's cracked up to be, it is not as good as people say it is. Her latest book isn't all it's cracked up to be. I wouldn't bother reading it if I were you. It's a good restaurant, but it's not all it's cracked up to be.
Q2: To get laid is to have sexual intercourse. (slang)
Q3: Yes! I'd take it at face value. The 21 year old had sexual intercourse several times, in spite of having unattractive teeth! (Not as attractive as a 21 year old with perfectly straight teeth!)