1. on the day of check in, when you're offered a cash upgrade to business, do basic economy and economy passengers in higher fare classes get the same cash offer?
2. economy and premium economy?
3. is award space, upgrade spots for SWUs, and upgrade with cash and miles all pulled from the same inventory? eg. if i see a business seat open on award space for a flight, can i also buy an economy ticket (even basic) and immediately upgrade it to business for $350 + 25k miles?
4. if i upgrade with cash and miles, is my new ticket treated as revenue in that class? i thought not, but had a BA flight i upgraded to first with miles and it credited as first (AA purchase, BA operated, AS credited)