WW EDR Mastercard - apply, or is there better?

[paultiffen]

You can do better by buying gift cards at 5% discount and use those for shopping + swipe the ER card

 

[NM]

What's the ratio for conversion back from 3 Amex points to X AA(or QFF) points?

Conversion rates already posted by another member.

Can you use a combination of AA and QFF to purchase tickets?

Each program can only be used for its own redemptions. I have a bank of AAdvantage miles and QFF points and use them for different things. I use QFF points for flight upgrades and I use AAdvantage miles for premium cabin international flight awards. So my card use works for my situation.