Hello.

1) When the booking have created (visitor click on "Send" button in the booking form), so then is executed this hook:

do_action('wpdev_new_booking',$booking_id, $bktype, $str_dates__dd_mm_yyyy, array($start_time, $end_time ) ,$formdata );

You can catch it:

    add_action('wpdev_new_booking',  'your_booking_created' ,1,5);
    function your_booking_created($booking_id, $booking_type, $booking_days_count, $times_array , $booking_form ){

       //debuge( $booking_id, $booking_type, $booking_days_count, $times_array , $booking_form );   // Show info  about parameters
   }

Disclaimer. Unfortunately we can not start, right now, some personal customization or custom development, because almost have no free time. Thank you for understanding. Please note, if you will modify the source code of the Booking Calendar, we will not guaranteed the correct work of plugin and do not support it.

2) Please note, in case if you need to delete specific booking (because of your quota), you need to run this code.

        $approved_id = array( 10 ); // ID of your booking(s) to  delete
        $approved_id_str = join( ',', $approved_id);
        $approved_id_str = wpbc_clean_like_string_for_db( $approved_id_str );
        wpbc_send_email_deleted( $approved_id_str, 1, '' );
        global $wpdb;
        if ( false === $wpdb->query( "DELETE FROM {$wpdb->prefix}bookingdates WHERE booking_id IN ({$approved_id_str})" ) ){
            die();
        }
        if ( false === $wpdb->query( "DELETE FROM {$wpdb->prefix}booking WHERE booking_id IN ({$approved_id_str})" ) ){
            die();
        }

Kind Regards.