For the domestic flight, having ROP or *A Gold status assists in getting those seats. I've been on flights where C was not full, but some pax (me!) were setaed in the F seats. Of course, you gotta be on a 747 BKK-HKT-BKK in the first place.

Exit row and bulkhead seats are not supposed to be allocated until actual physical checkin on the day, however, I know that TG does allocatethese preferentially to well connected Thais even before the 24 hrs period. By allmeans, ask your TA to place a seat request for those seats, note your status (are you *G?), and check in early....good luck though!