I created a few Facebook applications in December/January (practically forever ago now, I guess). Back then, and I assume now, their approval process for the directory was no big deal. Like, unless your app was explicitly pornographic, approval was a sure thing.
You could (can?) leave your app in "public beta", and it would still function just fine, without needing any approval. Considering that the directory will get you ~0 installs (who the fuck browses the facebook application directory, really) - if your app is super sketchy, just don't bother submitting it.
As for getting traffic and ultimately money - good luck. That shit was already super saturated a year ago. It's probably almost impossible now. If you want to get in the application game, look at some of the other networks. Almost all of them have application API's, and they are a lot less competitive.