The high crotch peak out is a great move that uses your opponent sprawl against himself. As your opponent sprawls, you get to the outside of him and before your opponent realizes it, you've taken his corner
22 is a great age to start. I was a wrestler for all my life, but didn't actually pick up any form of Mixed Martial Arts until after I left high school.
All else equal, in all martial arts, being stronger is better than being weaker. There is no way around this fact, but to what extent will strength training help your jiu jitsu, or your MMA. As is true with most sports, a strong cross-training regimen is important, but not nearly as important as doing the sport itself!
CrossFit absolutely works your entire body. CrossFit believes in the fitness methodology "Constantly Varied, high intensity functional movements". What does that mean?
I put a pretty heavy emphasis on using the Martial Arts that have proven effective in the UFC. In my opinion, all martial arts have a place in the world, but because I fight professionally, I feel I need to be versed in the hand-to-hand combat that has proven most effective amongst professionals.