SlickNick:
What you need (both skills and equipment) depends on the specifics of the dive. The important thing to recognize is that a "wreck dive" tells you about as much information about the dive as being told it is a "reef dive."
On Bonaire there is a wreck called the Hilma Hooker. It lays on the side with one rail being at 100FSW and the other probably being at something like 60 FSW. So, as a boat dive, it would be a fairly easy dive if one kept to say 60 FSW and you just saw around the wreck. No need for special equipment (perhaps a light to peer into a few portholes). Minimal current and a water temp of probably 80ish.
Now take that same dive and decide to make it a deep penetration (say the engine room) and it is a different story. The same with higher current dives like the Dwayne or the Bibb in Florida. Or the cold water and limited viz dives off of New Jersey. Or a deep dive like the Windjammer (also on Bonaire).... Everything is different -- from equipment to planning to execution.
I appreciate your interest in wrecks, here are some things you might want to think about.
1) Build your foundation of diving skills. Master bouyancy control. Improve your SAC and trim. Become very comfortable in the water. Master recovery from potential problems like lost mask, lost reg, OOA, etc. These will serve you well no matter what/where you dive.
2) Seek out a dive mentor. Seek out an instructor. Ideally, they both have some wreck interests or experience. They will help you grow as a dive. Learn about the many different training options -- GUE, PADI, NAUI, TDI, etc. And then dive!
3) Hold off on buying any expensive equipment for right now. Don't buy that Black Diamond BC with the big d-rings thinking that is what most wreck divers would use -- you may end up needing something else (like a backplate, wings and doubles). As you get further along, it will be more obvious where to invest your money.
4) Learn to use any new equipment and practice that in a lower risk setting. 100 FSW and 3 knot current is not the time to learn any new task (let alone something like a reel or a SMB). Learning should happen with a well qualified individual (could be an instructor or a mentor) helping.
5) When you are ready to progress in your diving, get additional training. When you need (not simply lust after) a piece of gear, buy it.
To answer your Nitrox question, SCUBA typically uses compressed air. If you increase the percentage of oxygen (and reduce the percentage of nitrogen), you get something commonly called EANx or Nitrox. The advantage of Nitrox is that you can extend your NDL bottom time. But that comes with risks from increased oxygen exposure. All manageable but that is why you take the class...