NFC is passive until powered by an external signal. It's very short range, but it does not require internal power. There could be a longer range version at some point.
Yes, but an NFC tag cannot initiate a connection on its own volition. And that’s very much a feature I like in WiFi: I can actively start downloading something. A WiFi card that only responds to an external ping is useless.
I think what berbec is saying is maybe you can locate an NFC device that has a depleted battery.
That said, I don't know if apple NFC works that way. Apple can use NFC to read nearby NFC tags, and possibly become an NFC tag, but I don't know if it can respond in a static way without power.
