Yes, Jio Phone 2 does support the Bengali language.
Yes, you can use WhatsApp in Jio Phone 2.
Yes, Jio Phone 2 comes with pre-loaded FM radio. You can even record songs which are broadcasted on FM radio.
Yes, Jio Phone 2 comes with the pre-loaded Facebook application.
No. Jio Phone 2 does not have the front camera flash.