No. Sony WS623 comes with non-removable battery.
No. Sony NS-WS623 does not have FM radio.
Sony WS623 has 4GB internal memory and you can further expand it up to 16GB with the help of MicroSD card.
Yes, you will get a pair of normal earbuds and a pair of swimming earbuds.
Yes, Sony NS-WS623 is meant for the rough usage and it is both - waterproof and dustproof.