Lots of questions and a first
Lots of questions and a first time triathlete! Dirtbag like.
Point by point:
1) 71 is plenty warm, I don't imagine you'll need a wetsuit. If you have one AND you've worn it before bring it along. They will probably announce if the race is wetsuit legal during the pre-race meeting. Your packet will probably also say. Normally there is a minimum temp for it to be, and 71 sounds high. You could, but then your time won't count. I wouldn't.
2) What you do in transition is up to you. If you want to deck change into cycling or running shorts then wrap a towel and go for it. Remember, the clock never stops. But if you aren't concerned about your time (and don't be, its your first one, it should be fun) and feel more comfortable wearing something else for the bike and run then change. Discomfort will ruin a race as fast as anything else. If you want to spend money you can buy
tri shorts, which are good for swimming and have a cycling pad, but its really small so that it doesn't soak up water and give you diaper butt and you can still run in it.
3) Triathlons are not draft legal. Three bike lengths is a good following rule of thumb, and fifteen seconds for passing is normal. If you are being passed it becomes your responsibility to get out of the draft zone. They will give you a time penalty if they catch you. Details should be given in your race packet and the pre-race meeting.
4) An Olympic isn't really long enough to need to eat during. At the most you will be out for three hours. If you are used to using GU on the move and you feel comfortable with it then bring it along and make the call during the race. I didn't during my Olympic. If I took it at the end of my ride, I would have a 50-ish minute run left, and by the time I'm done the calories are just starting to kick in. Not worth it. But its your call, you know your body. Keep one or two water bottles on your bike to hydrate during that portion. There will be aid stations through the run course with awesome volunteers handing out water and (probably) Sport Drink X. Your race packet will probably say how many aid stations and how they are spaced.
5) I would pack a spare if you have a seat bag, and a pump if you have one of the small ones that clips on to the bike (
example). There will probably/maybe be a Sag Wagon provided by the race to help people with flats as well. Best to be prepared.
6) The barefoot DQ thing is on a race-by-race basis. You could probably email the race director and ask. Your packet or the website might say. I would ask. Will you still do it if they say you can't run barefoot without being DQed? They (probably) won't pull you off the course for it. They just won't give you an official time.
EXTRA Info:
Smile. It should be fun or why did you spend the money and get up so damn early?
If you aren't comfortable in the water hang back, control your energy level, and survive it. Many triathletes do that.
Practice your transition plan and setting up your
transition area a few times before race day. Race day, with a high heart rate and people going all over the place, is not the time to experiment.
When you get there, after you put your bike away in the transition area, walk the path from the Swim Entrance to your bike to the Bike Exit, then from the Bike Entrance to your transition area to the Run Exit. Few things are more annoying then getting lost in the transition area and not being able to find your bike/gear.
Have fun. Did I mention that aleady?
Good luck! Let us know how it goes.