With all the travel around Australia, I don't agree that Star Alliance's products would be a better fit, but I DO know that you'd be in real trouble keeping within their mileage limits given your itinerary.

I'd recommend reading the Oneworld Explorer FAQ at the top of this forum; it will help address a lot of your concerns. Or, if you're a comparative newbie to the whole field of RTWs, you might want to look at a thread I posted on TripAdvisor that covers the field more generally.

One of the big considerations in planning and purchasing RTWs is the fact that prices vary hugely depending on where you buy and start/finish the RTW. This is especially significant if you're planning to fly in premium classes, where the difference in price between purchase locations can be as much as 100% or even more.

Regarding your specific plans, I wouldn't worry about POM causing the tool to balk; it's very buggy in the first place. Just leave POM out of a "trial" booking and the price you'll get will be very close to the price with POM included. You may need to purchase a ticket without POM, then add it back with a real human doing the changes. This would require the ticket to be re-issued (US$125) but it would speed things up tremendously.

Including ADD and CPT in one RTW is difficult, so doing ADD by itself might be the best option.

You might look at starting your trip in South Africa, as prices there are among the lowest for Oneworld RTW products. Obviously you'd need to factor in the cost of getting to SA in the first place, but especially in business class, RTWs originating in SA can be cheap enough to justify the "access" costs in the first place. If you DID start in SA, you can finish anywhere else in Africa, so you could get to ADD (from DOH) to end the trip.