How good was the food in the prison and did the prisoners ever get to leave if their sentence finished?

I don't know about the food i assume it was pretty basic. Prisoners would leave at the end of their sentences the same as any other prison. Al Capone spent time in there and was released at the end of his sentence.

But what about the other prisoners?

According to the signage on the tour, the food was very good, and the staff and the inmates ate the same food.