And the response to my USAirways question when a fare goes down after purchase ....

Dear Ms. 

Thank you for visiting usairways.com.

When a new lower fare becomes available after a ticket has been 
purchased, customers are entitled to a lower fare guarantee refund 
within the following guidelines. The difference in fares needs to be 
more than the change fee of $150.00.  The change fee will be deducted 
from the difference and the residual amount will be issued in the form 
of a US transportation voucher for future travel.  Additional rules and 
restrictions may apply. 

The lower fare is available for the exact itinerary previously 
purchased.
No portion of the reservation has been flown.
Lower fare guarantee refunds are not available for online ticket 
exchanges. Certain promotional fares may be excluded.

For domestic reservations please call 1-800-428-4322, for international 
reservations please call 1-800-622-1015 to seek a lower fare guarantee.
    
If you have any further questions or concerns, please feel free to reply
or call our Internet Support Desk at (800) 327-7810.  We know that you 
have many choices and we thank you for choosing US Airways. 

Sincerely,

Karilyn Smith
Internet Support Specialist
US Airways