I wonder if my intended strategy can work.

I am currently MPC - bearly reaching Gold (if at all). I prefer flying on CX and hence have not yet joined AA. Although I do not have a lot of flown miles, I get a lot of credit and other consumer miles - well over 100,000 miles a year.

But from what I read here in FT, AA miles go a lot longer for upgrades and rewards. My main area of interest is getting upgraded or redeeming for long haul tickets, on CX, which means using HKG as gateway.

Therefore, my intended strategy - keep existing MPC account but start AA account and work on accumulating AA miles, not by flying , but by credit card etc. This takes less to upgrade/redeem. But some Qs-

Q1 - Is it a lot more difficult to redeem CX upgrades and flights using AA miles (as opposed to using CX MPC miles?)

Q2 - I never really understood the point about upgrading using AA points. From what I know, a US-HKG flight upgrade from econ-bus is 25K (return trip). For business to first, it takes 40K. But from what I read here, the econ ticket has to be full fare? What about the business ticket if I wanna go to first? Also, could I upgrade 2 segments of a ticket, eg with ticket JFK-HKG-MNL and return, can I just upgrade the JFK-HKG segments?

Q3- As I understand it, the upgrades/redemption on CX using AA pts can be ex-USA or ex-HKG. The pts used are the same. Or must the tickets be ex-USA?

Could the gurus here please enlighten me? Thanks.