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First of all, please post your questions only one here on these forums. Your double post has been removed.
Second of all, the whole userinfo page works based on UID, and a numbered value. Changing that to a text variable isn't easy and not very safe (what is someone has a space in his/her name, it will not work). But you could check userinfo.php, and see if it is possible to change UID into UNAME or something.
But again, it is not easy to do.
Herko