404,
I don't think the number of days you are quoting is much of an issue, as the SOs in SIN would almost exclusively be crewing trips from SIN up to LHR/FRA and perhaps back to BKK or HKG. The only trips back to Australia would be for cyclic sessions, EP training etc plus holidays of course.
I understand what you are saying re: taking Qantas' word, but things such as the 180 day rule and min 2yrs for taxation have already been raised by the company.
I also heard $50k but that sounds a little too good to be true, I tend to think it was just a management spin on things.
TL