Food carriage?

on the train is the food carriage at the front or the back?

also, which is best on the hard sleeper? Middle or bottom ? it wont matter if lying down i guess.

The food server will come to you. Usually with a cart of food and drinks.

One train i went on had a restaurant

On the Bottom, you can use it for a seat as well.
It also cooler.
It you wants guests though sit up , otherwise lie flat for the trip.