How did Stalin's death affect the USSR and Eastern Europe?

Tremendously. Stalin was the USSR everything it was up to his death he had built. But not without getting a lot of hatred on the way. Following his death Soviet leaders had years or "de-stalinization" basically undoing everything he had done. Which lead to the collapse of the Soviet Union in 1990. After the dissolution of the Soviet union other areas that were claimed by the Soviet Union became independent.