Yes, it does support FM Radio.
Yes, Moto Z2 Play comes with latest Android 7.1 Nougat OS and does support Screen Cast.
You do not have to do anything special to avail Jio offer on Moto Z2 Play. Just when you start using the mobile, insert your Jio sim and it will get activated by the Jio company itself.
Yes, it comes with LED flash light with front camera.
Yes, it does support 4k Videos shooting as well playback.