Drupal Affiliate website

I have a drupal website, I need to following tasks: 1. I have installed the referral module + subdomain module. what I need is option for new-user to join in through already-registered user, by going to the already-registered-user-profile and register. I want to a new user to be able to register fast, just by going to already-registered user profile, over there I want register fields (username, password, email, etc) without the need to press on a "register" button. example: user named JOHN own a subdomain called: [login to view URL] new user named MARIA goes to jhon profile, there she will find fields which she will be able to fill up with information about her-self, without the need to press on the register button. 2. if possible - an AJAX plug-in that will show a user if the user-name is allready taken or not. I guess it can take from 1 to 4 hours of coding.