1. It'll become a AAdvantage card, but still Barclays. Details can be found in this thread:
Barclay US Airways Card Becoming AAdvantage Mastercard.
2. Availability of award seats after FFP merger is probably a valid concern, it seems to me.
3. That said, I think it's worth getting both cards for the bonuses; I just did the reverse, adding the USAir card (when the bonus got upped to 50k) to the AA card I got several months ago.