Customizing the sign up page for miltisite

I would like to customize the signup page for my multisite installation.

Please have a look at http://hqcelebrityphotos.com/. I would like to have a sign up page like edublogs or wordpress.com

1. Instead of two steps how can I make it in one page?
2. Design.. Which file needs to be edited to make it look according to the website theme. Can this be done from worpress admin area? Such as editing a page layout or post layout.
3. Make it domain.com/signup instead of domain.com/wp-signup.php
4. Remove the option of "Give me a site! & Just a username, please." and making it default to a new site for every signup.
5. Check the username, email & blog address availability instantly (whilst typing) instead of checking it once click submit. Like in wordpress.com
6. Language options like in edublogs..

Your input is really appreciated...