Identity of an Auschwitz prisoner

I wonder why the Nazi's separated the men and women. I don't see anything wrong with keeping them together. I also want to know what the prisoners were given to eat, but why would they have been given anything to eat? The Nazis wanted them dead anyway. What is the point of wasting food on them if you are going to end up killing them? I do think it is good that they were given food, because without the food we would not have any survivors.