I need some help from the experts.
I'm trying to plan a trip that involves Vietnam, and I cannot use CX flights out of Hong Kong. So the only other way I've found to get ther is to use the QF codeshare operated by VN (this is allowed). Is there another way?

One problem with this plan is that I want to do Asia first and then Australia later, but if I use the QF flight and connect in Australia, they won't let me go back, right?

One last question on the mileage on connecting flights. Do they count each segment separately, or do they use the origin-destination?

Thanks.