Welcome meadowfield,

A few comments about your plans:

When purchasing from BKK, you do not have to pay until th eticket is issued and the only requirement on a DONE4 for ticketing is 1 hour before the first departure. But you can hold reservations for any valid flights for as long as you like before ticketing, and seats can be allocated at the time of reservation not ticketing.

But we know from experience that the ticketing process for a comples DONE4 is not trivial and will likely take several hours, so allow enough time. But feel free to start the reservations as early as you like.

I can't find a BKK-PEK direct service on a OneWorld carrier. The best I can find is two sectors being CX to HKG and the DragonAir to PEK. DragonAir is not a OneWorld carrier and hence cannot be used on a OneWorld Explorer ticket.

Similarly, I can't find a PEK-KIX option for you on OneWorld Carriers.

You have two US Transcontinental flights included. MEL-JFK is not a single flight, so you either take QF93 MEL-LAX and QF107 LAX-JFK (using the US Trans-Continental) or a domestic MEL-SYD and the QF107 SYD-JFK in which case your US Trans-Continental is still available to you for BOS-SFO as planned.

Also note you can only do one Australian Trans-continental flight. These include flights between SYD/BNE/CNS and PER, as well as MEL/SYD and DRW. You have MEL-DRW-MEL which is two trans-continentals in Australia. Although MEL-BRM is not currently listed as a trans-continental flight, don't be surprised if it does get included now that QF are offering this as a non-stop service.