Planning RTW from Australia. Thought I had the whole thing sorted, but looks like I have more planning to do from trawling through some of these posts.

Already Platinum, so I care more about points than SC's. Also keen to use all 20 segments.

Questions:
1. What eactly is a segment? I think I am right in assuming that it is one segment so long as the flight number doesn't change - eg LA 601 LAX-LIM-SCL is one segment, not two???
2. Best way to come back from the US to AKL?
3. QF codeshare on AA flights seem to be resticted to trabnsfers from longhaul QF flights - correct? Are there any other code share options available on AA within US worth exploring.
4. My strategy is to maximise QF flights, avoid BA and AA, and use others as a compromise where necessary. Makes sense I think?
5. Anyway to get to SGN or anywhere in Indochina (CX flights b/w HKG and Vietnem are excluded).

Any other tips gratefully recieved. Many Thanks.