Maximising QF status credits with transcontinental AA flights - LAX>MIA

Looking for some help and clarification from the ET community.

I have some upcoming USA travel to LA. As a Qantas FF Gold, I am looking to maximise SC earn on domestic U.S. travel with AA given the recent changes. Flying from LAX or SNA to Miami. AA is the logical choice and dominates on the route, happy to hop skip and jump, but it appeared the best SC earn was transcontinental.

From what I have read, Qantas classifies multiple cities on the "West Coast", for "Transcontinental flights". This includes LA, SF, and Phoenix.

LAX > MIA > LAX - Economy - 35 SC (70 Return) $700-900
LAX > MIA > LAX - Business - 100 SC (200 Return) Around $3k
LAX > PHX MIA > LAX - Business - 40+100+100 (240 SC) Around $3k
LAX>MIA looks to be served by a mix of 321 but also a 777 at the moment which seems to be the pick.

My work is far closer to SNA (Orange County) than LAX, but previously prior to the joint venture, any AA SC wouldn't translate to Qantas SC, now it appears thus gas been fixed on the calculator.

SNA > PHX > MIA > LAX - Business - 40+100+100 (240 SC) TBD

I have a AA membership but primarily a QFF.
Should I book these flights logged in to my AAdvantage account then simply apply by QFF? Or should I book, not logged in? I want the best change seat upgrades or any One World benefits. I do realize I can always ensure the FF number is Qantas at check-in, but desired the ability to select my seats which no status with AA won't give me without $$.

Any thoughts on which LAX > MIA or SNA > PHX > MIA and SC calculations?

I booked a range of US domestic sectors flying AA via Google Flights as it was seriously cheaper than the AA or AMEX website. The points haul was abysmal but at least I picked up status credits.

I was flying discount economy.

They are all harmonised now so it doesn't matter which scheme you use, seat selection depends on price and status so as they say do the sums on the range you have chosen. Use the scheme which will give you the greatest benefit such as closeness to gold/platinum but do note qantas platinum opens more doors than AA platinum.

I assume that you don't have American Airlines elite status. You can book your flights anywhere. You just need the booking reference for the American Airlines system where you can then add your Qantas Frequent Flyer status. Given you will fly in business, seat selection will be free and there will be ample luggage allowance for you. As a benefit of Qantas Gold, you can also access the Admirals Club or Flagship Lounge before your flight. American Airlines elite status holders don't have this benefit. Only other Oneworld Sapphire or Emerald members such as Qantas Gold can access either the Admirals Club, Flagship Lounge or any other oneworld lounge before your domestic American Airlines flight.

I can't really add go the SC question but I have a place 10 minutes from John Wayne (SNA) and fly out of there on AA a lot. I generally fly to either Dallas or Chicago and connect from there. Phoenix is OK but there are more options via DFW.