Back in June 07 I flew from MNL to HKG on Cebu Pacific, then HKG to LAX on CX and LAX to SEA on AS.
In MNL they checked the bags all the way through to SEA.
However, you have to claim them in TBIT at LAX and go through customs/immigration.
I was also trying for an earlier flight from LAX to SEA, so as you leave TBIT, they ask when your next flight is.. if you tell them more than an hour or so, then they direct you outside and you walk/take the shuttle to your proper terminal (AS is right next to TBIT, so it's like a 5 minute or less walk).
I checked in at the AS counter and they tore off the Cebu tags and replace them with the AS bag tags.
I don't think that Quantas can put you on the standby list at LAX