No. You can use Instagram website but you cannot use the Instagram App on Jio Phone 2.
Yes, Jio Phone 2 does support the Bengali language.
Yes, Jio Phone 2 is a dual sim mobile phone. You can use 4G sim card slot with the Jio sim and another slot can be used with 2G network sim card.
No. Jio Phone 2 does not have the OTG support.
Jio Phone 2 does have the plastic keypad.