I'm very sorry you received incorrect information.
Yes, Disney will get your baggage and deliver it to your room regardless of the Airline you flight on, as long as you attach the special luggage tags we send you.
With US Airways, you will not be able to use the Airline Check-In service to get your departing boarding pass or check your luggage in the resort lobby, you simply need to do so at your Airlines check-in desk at the Airport itself.
If you know the name of the agent that gave you this information, PLEASE call back and ask to speak with Guest Services and report her name and the information she told you.
Just for your information, you will NOT be getting her in trouble. She will simply recieve a QC notice and be re-trained on the Disney's Magical Express / Airline Check-In services. This will help ensure others are always getting correct information from the Disney Reservation Center.
Hope this helps! :sohappy: