If you want to remove items from the toolbar you could try using $wp_admin_bar->remove_node
like so:
You’ll have to use an inspect element to find out the IDs but if you would want to remove the WordPress logo you could inspect it and see:
<li id="wp-admin-bar-wp-logo" class="menupop"> … </li>
Then you would target the ID like so:
function remove_wp_logo( $wp_admin_bar ) {
$wp_admin_bar->remove_node( 'wp-logo' );
}
add_action( 'admin_bar_menu', 'remove_wp_logo', 999 );
I’m not sure if Font-Awesome is installed with BBPress ( I know it’s not in WordPress ) so you’ll need to make sure you admin-enqueue the fonts first. Otherwise, you’ll have to work with Dashicons ( which is installed into WordPress )