To answer Q3 our AA Plat status did not give us any seating preference for our return SYD - JFK flights earlier this year.
In fact when I first booked through QF I requested 4 seats together in the centre and was even given the seat numbers. However when we arrived at the airport none of us were seated together despite all being on the same reservation number and all having the same surname!
Thank goodness we booked in 3 hours early as we at least were able to change to 2 and 2.