Yes, you can connect it with phone and talk and can use as a normal Bluetooth headset.
Sony WS623 comes with LED indicator. If it is not fully charged and require charging - it will show orange light and when it is fully charged - it will show green light.
No. Sony NS-WS623 does not have FM radio.
Yes, Sony NS-WS623 does have NFC connectivity option.
No. It does not have remote control.