Welcome Barb. You don't have to be into water sports to enjoy the PG, although it's a bonus if you like the water. You can enjoy the motu picnic without swimming (my husband has usually gone in the water once the whole week.) There are the 4x4 island tours, bus and "le truck" tours (open-air buses), a couple of hikes, some sailing, and of course shopping! Also events on the ship itself.

I can't comment on the New Zealand and Oz part of the trip, I don't know how that works. If you want to know if anybody else is contemplating the same trip, you might want to mention the dates you are thinking about.