Fine I will do the MMA section.
MMA is a full contact sport involving striking, grappling and groundwork. It combines elements of many martial arts that have been put together by legends in there respective fields.
There are no official rank systems some clubs may have internal ranks.
There are many different sorts of MMA other than just what people see on the UFC. Including limited rules for beginners and even tag team matches.
Pros.
A good balance of striking grappling and groundwork.
A competitive sport. One that can earn you money. Travel the world and meet different people.
A viable self defence method.
Cons.
It is hard. You do not get things handed to you.
No weapons. No de escalation. situational awarness and other things that are essential for self defence.
MMA teaches you the basic mechanics of fighting well. There is no illusion that there is a short cut to winning fights. Everything applied is resisted. Losing and failing is a real option during training.
My advice. Find a club with reputable fighters. Your instructor should spar and should be encouraging you to beat and test him.
kevin james training with Randy Couture - YouTube