"ince I have the original record locator and the second, would it be safe for me to just walk up to the airport on the day of the flight?"

If you are not booked on the flight , I wouldn't say so.

"Is there a way to confirm my seating on the flight without going through the airline telephone holding system? I literally waited for 20 minutes last time!"

If you are in Sydney , you could pop into the Qantas Travel office in the City. They will be able to do it for you if you dont want to call. Alternatively, if phoning, try calling late in the evening.

Dave