I wrote an article over on vb.com on how to move the facebook stuff from the header to the navbar template. It talks about a plugin to preregister the variables. Read that as it is going to be exactly what you will have to do with the variables in the username/password/welcome area when you move them to the navbar template.
I know not the facebook only. I was saying to look at that article to find out about preregistering the variables for use in the template you are moving your login info to.