Sony NS-WS623 is quite light weight. It weighs just about 32 grams.
Yes, Sony NS-WS623 does have NFC connectivity option.
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.
Hold down the button 1 for 3 seconds.
You will hear the startup sound.
When the Walkman turns on, the lamp (2) lights up.