BuddyPress.org

hi vintagefan, you can use the plugin “Remove Dashboard Access” (by TrustedLogin) to restrict dashboard access to admins only. Search for it.

You can also hide that upper-left item from the admin bar with the following code snippet:

function remove_admin_bar_items() {

global $wp_admin_bar;
$wp_admin_bar->remove_menu('site-name');
}
add_action( 'wp_before_admin_bar_render', 'remove_admin_bar_items' );

You could use the standard Subscriber role for new users, they would not have dashboard access.