nfc on andriod

[seagate1]

near field communication, i have just discovered my sony wireless/Bluetooth headphones have nfc to connect to my phone lg. is it best to use it or Bluetooth, and do i have to leave it on once the device is connected. i have been reading about it but cannot find anything regarding to leave it on.plus it worry's me now reading about it. if someone as there's turned on, on there smart phone can they get information of the phone and visa versa. i know its got its good things you can do with it as like paying at these swipe things i dont trust that so would not use it for that its mainly for the headphone because if im right it does not drain the battery like bluetooth i have the app on my phone. just need some information please thank you.

its getting more confusing now just discovered you can get different tags for nfc.