I agree with basking. nitrox is not that big of a deal anymore. go ahead and take the class. you may even could do it online before hand.
diving with sharks is a totally different deal. Whether you love sharks or not, you are still a newbie. Get some more dives under your belt before you are put into a situation that is more than unpredictable, with wild animals, that can severely harm you even by accident. I personally do not care for "baiting" the sharks to come in. It starts them to associate humans with food (just my opinion). New divers get "antsy" all the time and when they do, they bolt for the surface. bolting for the surface is bad enough, but to do it during a shark feed is down right dangerous. Log some dives, hone your skills and get super comfortable underwater before hanging out with those multi-toothed goldfish.
All that being said, this is a VERY safe sport when you respect it and dive within your training. Welcome to this wonderful cult, lol.
If you ever have any questions, feel free to ask.