Jio Phone 2 does have the plastic keypad.
Yes, you can use WhatsApp in Jio Phone 2.
Yes, Jio Phone 2 comes with the pre-loaded Facebook application.
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 does have the Gujarati language support.