Your interpretation of the rules is correct. You do have to publish through us to count as an entry. On the rev share split: if a user spends $99c on your app, Apple takes 29c, we take 20c (70% post-Apple), and you are left with 50c which is just over half.

Our publishing contract is very developer friendly - we don't take ownership of any of your IP. So, you could publish your game with us (and we'd probably end up touching up some art here and there) and if you didn't like what we were doing with it, you could publish a version yourself. If we aren't worth it, you're not tied to us. If we are we hope to publish a bunch of your games :) Very low risk in giving us a try if you already have a game on the way.