Hello

I have an idea for a facebook application and I am in an early stages of finding a development company to develop it for me. I brief I can tell you my application will be a simple image manipulation on facebook where users can edit a bunch of images and email it to their friends. Imagine a very simple Photoshop interface on facebook, eventually what I would like users to be able to do is to send the images they generate to a mobile phone. Now at this point I am just gathering information that could help me determine the possibilities as well as a rough cost estimation, and I have the following questions. I would very much appreciate it if anyone can provide me some information.

What should be the user interface for facebook apps? is it only flash or could it be anything else?
Can any kind of 3D content be used in facebook apps, contents that the 3d game engines use, like the ones on iPhone?
Would facebook charge anything to make facebook applications or to publish them?
Can facebook applications ask users to pay money? Or should they always be free?
If a facebook application charges its users, does facebook foundation get a share of it?
If I have a facebook application can I directly access it on my iPhone? without going through facebook?
How long does it take for a facebook application to be validated?

Thanks you so much