on the log in page, edit the security assist authenticate user behavior, on the session tab, add the username and user group column to be stored in session variables.
use the user name session to show the user name
as for editing the user info, it would be best to user update page and an admin page for the admin to update the users.
create the admin page using Data Bridge for the users table to create search, results, insert, update and delete pages. the create an admin rule to restrict access to those pages to the admin user.
there is a tutorial for user level access here:
is was written for V1, but the concept is the same.