well, i think you don't need make any changes to that ezuser table. i mean, you can add attributes to the user class through the admin interface. so, these new attributes (birthday date, favourite movies and so on) will be part of the data_map of the object for the users, along with firstname, picture and so on.
favourite movies could be a relation objects to other type of objects, for example.
Maybe this contrib
http://ez.no/developer/contribs/import_export/user_creator could help you with your work.
