There's currently only 4 747-300s in active service with Qantas.
743s are useful in covering 744 maintenance and operating flights that may need extra capacity during busy holiday times, such as SYD-NOU/HNL. BNE-PER-BNE is still slated to get 743s on the ~8.30am flight later in the year.
1 747-300 will operate a Captain's Choice Tour later this month.
You won't see a 747-300 on QF9/10, but it's always possible you may see a 2-class 747-400. The 747-300 has operated QF127/128 (normally 3-class 744) in the past before, but you have to remember this doesn't continue onto LHR, like QF9/10 does, and there is no way Qantas would operate a 743 and Dreamtime to LHR - I mean they would rather cancel BNE/MEL/SYD-LAX flights and use the aircraft to LHR.
AVOD was installed on the final 747-400 in early March 2007 - so all of fleet has had it for a little while.
Rgds