Don't really have any inputs on #1 & #2 except: having found it a tad hard to stick to AA for my flights within the US, given the 'smaller' AA footprint in the places i need to frequent, i see US' network as adding value (fewer and better connections), if those flights are kept.

3) No data, but i doubt we'll see CX's lounge network getting overwhelmed (US was small, and i'd hazard to say that their FF program rather weak in absolute numbers).
On the other hand, I hope that the newAA keeps the customer service levels that i've experienced from the AAngels at the ACs/FLs (they were called that, and not dragons for a reason!).

New OWE benefits notwithstanding, AA was generous to OW elites, for MPC Gold/Silver members as well (baggage, priority seating, free standby, and even upgrades) - hope that carries through.

My experience as a OW Sapphire and Emerald with AA has been way better than it was with UA as a SQ *G, one can hope.