Yes, it does have fast charging. Charge it for just 3 minutes and it will work for another 60 minutes.
Hold down the button 1 for 3 seconds.
You will hear the startup sound.
When the Walkman turns on, the lamp (2) lights up.
Yes, you can connect it with phone and talk and can use as a normal Bluetooth headset.
No. Sony WS623 comes with non-removable battery.
Sony WS623 has 4GB internal memory and you can further expand it up to 16GB with the help of MicroSD card.