How to add additional information to a user on user creation?

I’d think you’d need to hook into the user_register action, like recommended above, and then use some code similar to this:

add_action('user_register','post_user_reg_redirect');
function post_user_reg_redirect( $user_id )
{
        if ( is_admin() ) {
             wp_redirect(get_edit_user_link( $user_id ));
             die();
        }

}

This would check that you’re creating a user in the admin view, and then redirect to the edit user link of that newly-created user.