You will earn Avios through purchases on your credit card, which can be either put into an Avios.com account, or BAEC account (and freely transferred between the two).
You will earn Qantas FF points for your flight.
If you are in the UK, if you don't have many Qantas FF points it may be worth switching to BAEC.
Agreed.
The upgraded BAEC is now an infinitely more generous programme compared to QF.