Nickname & Status Message

You can change your name in the Google Account page.
or To change the nickname need to go to your Gmail account and change the name there. Choose Settings, Accounts, and then Edit info. Click on the second radio button, and enter your custom name.
As a result all of your emails will have that nick as well, there is no way to seperate the two.
You can add a website in your custom message, it will be clickable when someone opens a conversation window with you.