One problem I see is the KUL to NRT - you can't fly on JAL metal on a OWE - it has to be OW metal, which would eman CX via HKG, but that puts you over the 20 segment limit.

SInce you only have 4 hours in KUL I guess you don't have to do anything there as such, so just BKK-HKG-NRT on CX would do the job.

1) No
2) Yes - IPC and PPT (requiring using someone else to get from PPT to SWP). Lord Howe Island has been recommended by others (QF from SYD).
3) Also from DFW and STL and occasional flights which stop there but have a single flight number from somewhere else (e.g. CUN). But only June to September)
4) The shortest way is via TPE on CX. Requires two segments.
5) Perhaps true according to other discussions here.