2. A wetsuit isn't a necessity, but it may be helpful. I remember the water being cool, but not freezing last year. Post on the board and someone may be willing to loan you one that they're not using that weekend.
3. My aerobars are on my road bike. I don't have a tri bike, so my Giant is adapted for triathlon racing. It works wonderfully! It's a great (read: less expensive) way to do triathlons without buying a tri specific bike.
Vash, Tanya caught most of the websites. There's also some good books, like Swim, Bike, Run by Wes Hobson.
For a 500ms sprint distance, I wouldn't worry about wetsuit. Unless you can strip like a hooker, the time you save with a wetsuit may be lost in transition trying to get out of it.
Aero bars can easily attached to a road bike. You can find low-end Profile Design on eBay for $20.
vash: My favorite books are "Breakthrough Triathlon Training" and "Scientific Training For Triathletes". I've since learned that the former is on shaky scientific ground, but it's prescription is still spot-on. Basically long overdistance workouts - all the swim/bike/run you can handle at easy to moderate paces. The "Scientific Training.." book is necessary if you're going to read forums where all sorts of weird/bad advice is bandied about.
IMO, they are better than nothing, BUT I would spend a little more and get something you'll be happier with for a bit longer. Most people tend to get sick of the solid, 1-piece aerobars once they get into the sport. I think of all the aerobars, they are the least appealing. May want to be more patient and wait for something else to come along, but ultimately, it's up to you if you want to buy them.