Instead of creating yet another username and password, will use the account you select above. If you don't see your institution or a social identity provider that you want to use, you may have an OpenID you can use from another service such as Flickr, Blogger, or WordPress.com account - click the OpenID logo and then the icon for the corresponding service, and it well help you find out your OpenID URL.
No. After entering your info above, you will be taken to the service that you picked and enter your password there. Then you will be asked to approve to have limited access to basic information like your username and email address. Finally you will be redirected back here to finish signing up. We will never have access to your passwords or your accounts.