The following is some advice I gave to a beginner triathlete who was trying to work out some strategies to avoid blowing up on the run.
Welcome to the sport, I'm glad you had a good time at your first race. Also glad to hear that you have found the swim workouts and articles useful. thanks!
My suggestion to you is a couple things for the next few days:
This weekend practice a brick workout - 10-15 mile bike followed by a 1-2 mile run. I would say do this at a pretty decent effort level. One of the problems people run into when they first start out, myself included, is that the legs just aren't ready for the feeling of getting off the bike and running, no matter what kind of base fitness you have. The only way to prepare for this is to do bricks.
Long term- try to do a brick workout once every week or couple weeks to prepare for next season. You can vary it as you increase distance in your training, but the most important thing in sprints is to get ready for that first mile, like you experienced. ouch, eh?
Regarding effort in the swim and bike - yes, I think you would probably have a better experience if you backed off on effort in both, but by only a small degree. Instead of pushing it 100%, try keeping it between 90-93% effort (hard to do, I know - if you are panting, slow down or HR not more than 160-165 (where 170-180 would be going for sustained max speed)). I think you would have a better run (this time 3 miles) and no walking. The run is very important and with too much too soon in these races, you pay, as you found out.
Eventually you will get into the kind of shape where you can go near 100% effort the whole way. It can take a while, depending on how much you train, how smart you train, your genetics, your mind, and all other factors.
With splits and times - sometimes there are flubs. It happens less with races that use the chip. If you stick around for preliminary results and see an error, you can report it then and usually get it straightened out immediately. If you have to jett right after the race and then find out a day or two later, you can still report it but the awards are already given out, everybody's home, and frankly, at that point nobody really cares (except you, of course!). If that's the case the only reason to really press the issue is if you should have gotten an award, otherwise just know what you did and don't worry about it.
I won't be down there for August 26, I'm headed to Siesta Key this weekend and then Bahamas in 2 weeks. Have a good one and drop me a line to let me know how it goes!