No point in trying to get seat assignments for RJ. If you get one, its as good as vapor -- well not that good.
Good that you have your RJ PNR. Cute that it is a digit shorter!
Be sure to phone RJ 24 hours before flight to reconfirm. Be prepared to be on hold up to an hour or so... yes, I don't jest. Failure to do so will result in cancellation without DB if the flight oversells and reaccomodation only as standby. Do this on the return too. Reconfirming with AA won't do the trick.
NYC : 212-949-0050
AMM: 6 5100000
In Amman you won't have to wait on the phone long. You can also visit the ticket office at the 7th Circle (near the Safeway).
Best way between airport and the city is to take the RJ bus to the 7th Circle, then taxi from there. Taxis are generally honest.
Food options at AMM airport are poor.