KCargosfan.. SInce you asked...(and as I can't help with your other questions...

)
The majority of the worlds airlines are grouped into 3 alliances..
- The Star Alliance (airlines like Lufthansa,SWISS,Asiana, Singapore Airlines, United, US Airways etc)
-Oneworld (American Airlines, British Airways, QANTAS and others)
-Skyteam (Delta, Korean Airlines and others)
Some quite large airlines do not belong to an alliance.. such as Emirates.
What
RobertNC was referring to was the use of US Airways miles to "purchase" an itinerary from A to B on a combination of Star Alliance airlines....