Yes, Sony NS-WS623 does have NFC connectivity option.
Yes, you will get a pair of normal earbuds and a pair of swimming earbuds.
Yes, you can connect it with phone and talk and can use as a normal Bluetooth headset.
Yes, Sony NS-WS623 is meant for the rough usage and it is both - waterproof and dustproof.
Sony NS-WS623 is quite light weight. It weighs just about 32 grams.