I've done several troops now in just a month lol and have one tomorrow (xmas parade) and I can tell you this:
My first troop, I walked funny because of armor bite heh. My 2nd troop my thigh fell down (and had to have Han Solo stick his hand in there and fix it, picture WAS taken! ack) My 3rd troop my biceps twisted around entirely and looked really stupid heh. On my last troop one of my fans cut out, I ended up with a ton of sweat in my bucket that poured out.
My point! Don't worry! Things happen to (most) of us. It will you too. But it will be the most fun you'll ever have!
And as stated, bring that repair kit. I have a little 5 dollar toolbox with some velcro, scissors, my hot glue gun and glue, a leatherman, battery operated dremel with bits. Extra batteries, wire, a 2nd mic, glue, tape, etc. Already has come in handy!
You will do fine. As it was said, it doesn't matter what happens to you, people and kids are gonna go nuts and you will get asked to take pictures a LOT! Stick with other troopers and you will learn a lot of good tips and tricks, both in and out of armor.
Good luck and post picts when you get some!!