French Polynesia

It depends on the resort and which motu it's on: some near Vaitape village have good coverage, while more remote ones have weaker signal and lean more on hotel Wi-Fi. It's worth checking with the resort ahead of time.

Usually in the village near the airport, but noticeably weaker or absent further out. For islands like these, download offline maps and save key addresses and contacts before you fly out.

No, and you shouldn't count on it — signal is usually absent on the water and beyond the reef. It comes back once you're near shore or back on the boat.

Yes, the profile can be installed via QR code or quick install in advance, with data roaming switched on only after landing in Papeete, so the plan isn't used up before the trip begins.