What you need is very little (shoes, swim suit, bike and helmet), but there are lots of things that can make your training and race more enjoyable. Here are a few of the not essential, but awfully nice things to have IMO.

I agree 100% with everything that has been said above on the wetsuit. Rentals are a great way to go for your first race. Some places will send you the suit a week or two before the race so you can practice swimming in it and (more importantly) getting it on and off.

I think a nice pair of tri shorts is a good thing to have. In fact, it's very close to a must have. Tri shorts are basically lycra shorts with a thinner, quick drying chamois pad that you can use for all 3 sports. Wear them under your wetsuit and then just ride and run in them. Since you come from a wrestling background, I'm guessing that you aren't shy about wearing lycra.

I would also consider going with clipless pedals on what ever bike you end up riding. They are more efficient and the shoes have stiff soles that can save you a lot of suffering on long rides. You can get road, mountain or tri shoes, all of them will do. Just make sure that your pedals accept the same type of cleat as your shoes. Oh yeah, practice getting in and out of them and after a while not only is it second nature, you won't want to ride without them.

For long training rides a pair of good bike shorts or bibs (my preference) can work wonders. They're simply more comfortable to ride in than non-cycling specific shorts.

A full on trisuit is great for speeding you through the transition, but really it doesn't take all that long to throw on a loose fitting, quick drying t-shirt if you prefer.

Goggles or a mask are a must IMO. Can't imagine swimming without them.

Those are really the essential "non-essentials." Heart rate monitors, bike computers, aerobars, etc. are fun toys, but a little lower down on the must have list. Like I said earlier, I don't use aerobars because of where I ride, but they might work for you.

I think, based on your current fitness level, you have plenty of time to get ready for an international distance in late September. As part of your training you might want to find a sprint sometime in mid to late August in order to get a feel for the whole thing and gauge your fitness level.