Zero benefit from QF ffp compared to AA. And you are AA lifetime Plat.
Buying the AA codeshare for Aust-USA flights may cost more $ than the value of the 100% bonus benefit you would receive. You will not be able to buy AA codeshares for Au domestic flights.
For USA based airlines ffp upgrades seem to be an expected benefit/entitlement from status. That doesl not happen in Australia, even with top QF status.
For the value of QF points/surcharges vs AA miles look at
post 330. To me 2 QF points = 1 AA mile.
Several AA vs QF threads linked in post 2 here :
http://www.flyertalk.com/forum/onewo...help-here.html