It's such a fun ride, full of camaraderie (b/c unless your group fills a whole raft, they put strangers in the raft, and I've never had that NOT be fun!) and laughter, you shouldn't be scared. Plus, the last spinning drop can be watched ahead of time until you're totally comfortable with the fact that it's not THAT long or steep.
We definitely use the lockers...if you don't see them, ASK a CM! They are tucked away; when you don't know where they are, they are mystifying, but once you know where they are you don't know how you ever missed them. The lockers lock electronically, and you are given a slip of paper like a gas station receipt that has the code on it. So make sure you have *something* on your person that's closeable and waterproof (we always have lanyards with plastic pouches so they go in there) to carry that receipt in. So just bring a little pair of flipflops, change shoes at the lockers, and your "touring" shoes will be safe.
Little tip, since you hate feeling like you're falling. No one read if you don't want to know!
You go up, up, and up at the beginning. Although I feel that to be a good part of the ride, the unknown, I will give you info here. Most newbies think there's going to be a huge drop after, as big as the going-up was. It's not. It's a tiny little splashy blip.

So now you won't have the nervous, relieved laughter when that is realized, but you also won't have the dread, either.
There are a few downhills after, but they are short. The FUN of them is that you never know who is going downhill backwards. Beware of lording it over someone who has just gotten drenched...in my experience, the person who does that is the next to get soaked!
