I'm planning the following Oneworld itinerary and wanted to ensure that it met the LONE5 rules. Segments in (xxx-xxx) indicate flights purchased separately, while commas indicate overland segments.

(IAD-)EZE-SCL-IPC-SCL-GRU-NRT-PEK(-,HKG-DEL,BOM-BKK(-RGN-BKK),
SIN-SYD-CNS-AYQ-PER-JNB-(MRU-SEZ-MRU-RRG-)MRU-JNB(-VFA,)
DAR-LHR-THR,(DXB-)CAI-BUD,MAD-EZE(-IAD).
(note: IPC is the only stopover in S. America for now, but I might take a few days in Santiago if it's legal on the fare, which I believe it is).

I believe this is a legal fare, but my three main worries are:
1) Is SA-Asia-OZ-AFR-EUR-SA a legal "continuous direction" flight, or would they say OZ is East of Asia, not "even" as is the case with Africa/Europe?
2) Can I do the JAL flight from GRU-NRT without adding a sixth continent? The flight is listed as a direct from GRU-NRT, but goes via LaGuardia. The whole flight is JL048, I believe. I'm pretty sure this is the only SA-Asia direct on oneworld (maybe on any airline!) - is this right?
3) Is it legal to return to JNB after visiting MRU? I'm planning on the Comair flight starting in July (this ticket wouldn't begin until September).

As far as this itinerary is concerned, it seems to me that starting in EZE is cheaper than starting in the US, even with the RT to EZE added in. Would you assume this is the cheapest way to do a routing such as this? I'm not tied into Oneworld (actually haven't flown them in some time - I took CX, AC and NW on my last three intl. flights) so I'm glad to use non-oneworld segments. Also, is the rate from ARG still in the ballpark of 3500 for this fare (+tax)?

Thanks for the help.