describe the conditions first at the Birkenau reception center, then at Auschwitz, and later at Buna. How does Wisel´s relationship with his father change during this time?

They are simply all bad. The Jews are herded into cold farm-house-like structures. They are crowded in beds packed on top of each other. They are forced to lie about their ages and occupations. If they are not deemed "useful", they are killed and sent to the ovens. I don't think Ellie ever stops loving or caring about his father. Ellie has a crisis of faith which his father does not have. Still Ellie does his best to take care of his father despite the Hell they exist in.