Allowing others to sign up to post content

I am looking for a method to allow users to sign up to post on my blog. I want this to be fairly automated, meaning they fill out the form, I get an email, if I approve them they can post as many blogs as they want, but I must approve all blog posts from anyone other than me. I also would like the sign up form to be somewhat unique, and not say “wordpress” all over it, and that is about it. One other thing that I would love though, is if I could create a custom add post form for the writers, because for this particular blog, I want to limit them, and force them to complete all three, title, tags, category, and 3 custom values. I understand that this is a lot, but I am not asking for much more than a link or a few links to point me in the right direction. I have been looking around for a few days and I haven’t quite found what I was looking for.