Sony WS623 has 4GB internal memory and you can further expand it up to 16GB with the help of MicroSD card.
No. Sony NS-WS623 does not have FM radio.
You can check the charging status with the lamp ( 3 ).
While the battery is charging: orange when charging is complete: green
Yes, Sony NS-WS623 is meant for the rough usage and it is both - waterproof and dustproof.
No. It does not have.