Congrats and good luck! It will be great! I did the one last September in MD, the day of the massive thunderstorm.
It's less of a run than an obstacle course. If you can run ten miles, you will have no problem with this. Your team is your best resource. They will help you though the tough/scary obstacles. And there is no shame in skipping one here or there. I didn't feel the need to scale another set of walls, after I had done it twice already. You won't be the oldest at 40 either.
Wear long sleeves/pants - I have scars on my ankles from wearing shorts. If you wear gloves, don't take them off and put them back on; there are water obstacles, and your hands will get gross. Just leave them on or get rid of them. Wear shoes you won't miss.
Don't bother with goggles - it's not an actual swim, I'd carry as little as possible. You could try some type of Spibelt for your gels, but that might get annoying when you are crawling. They will have bananas on the course - I ate my weight in bananas during the event!
Enjoy it! It was more fun than scary - although they closed the obstacle I was most afraid of, so that might have helped me
