Couple of quick questions after toying with AA BA and CX codes on LHR-LAX and JFK-HKG flights respectively.

1. Does CX have lower fuel surcharges than AA? Was pricing out the DONE4 and using the AA code instead of BA (on BA metal) on LHR-LAX reduces the surcharges by 100$ or so while using the AA code instead of CX (on CX metal) on JFK-HKG works out to be 100$ or so dearer.

2. I know single flight numbers count as one segment (eg. SYD-SIN-LHR). Does that also apply if the two sections of that flight are flown on different days? (eg. SYD-SIN on one day and the same flight number SIN-LHR on the next day?)

As an aside, finally leaning towards crediting the DONE4 to AAdvantage as opposed to QFF due to AA's great rates on award tickets. An optimized DONE4 (with a Plat Challenge at the start) will net me close to 130k miles which is 1.5 RT Tickets (SYD-BOM) in Business (which is a route I fly fairly often!).

While I'll only make Plat (OWS) on AA as opposed to Plat (OWE) on QF, the redemption award rates win out for me when compared to the Partner Gold (which I could hit with a well optimized itin. + a N.America MR). Lack of lounge access in the US for AA OWS is not an issue.