Sony WS623 has 4GB internal memory and you can further expand it up to 16GB with the help of MicroSD card.
Yes, Sony NS-WS623 does have NFC connectivity option.
Connect the USB cable (supplied) to the USB cradle (supplied). Then, attach the Walkman to the USB cradle.
Make sure to connect the terminals ( 1 and 2 ).
Yes, you can connect it with phone and talk and can use as a normal Bluetooth headset.
Sony NS-WS623 is available only in the Black color.