See here and here. You are asking about AS-marketed, AA-operated codeshares.

On AA-operated flights when using your AAdvantage number, your MCE benefits will apply regardless of marketing carrier. But upgrades will not apply to codeshares (it specifies "American marketed and operated" -- you might have luck getting on the upgrade list at the airport on day of travel). The new policy allowing EXP upgrades on AS flights can be understood from context as AS-operated, so that doesn't apply here.

Baggage fee waivers should apply straightforwardly since you are checking in with AA.

Oneworld benefits, if applicable, will be normal since they include codeshare flights that are both marketed and operated by a Oneworld carrier (which both AS and AA are).