Hi Manboy,
It’s in the tutorial post (and I really would make sure that you read it first) but it means Posture and alignment, Pressure relief, and Personal preferences.
North American materials aren’t always better (it depends on the specifics and the quality of what you are comparing) and in the case of latex the type and blend of latex and your own personal criteria and preferences are more important than where the latex is made. I would also be aware that natural latex isn’t always “better” (depending on how you define “better”). There is more about the different types of latex in post #6 here.
Zoning can certainly be useful for those that are more difficult to “fit” to a mattress or when it is an improvement in terms of PPP compared to a single firmness but it depends on whether your testing or experience indicates that a specific zoning scheme is a good match for your body type and sleeping positions. There is more about zoning in this article and in post #11 here.
Phoenix