Short answers, pulled from the story.
Approximately three million German prisoners of war were captured by the Soviet Union during World War II. Soviet records list 2,733,739 Wehrmacht POWs, while the West German Maschke Commission concluded that 3,060,000 German military personnel were taken prisoner by the USSR.
Soviet NKVD records list 381,067 German Wehrmacht POWs dying in captivity, a rate of 13.9 percent. The West German Maschke Commission found 1,094,250 died in captivity, and German historian Rudiger Overmans placed the maximum at 1.0 million deaths.
The last German prisoners of war were repatriated from the Soviet Union in 1956. These were men classified as Kriegsverurteilte, or war convicts, most of whom had been sentenced to 25-year terms in forced labor camps. Their release followed direct intervention by West German Chancellor Konrad Adenauer in Moscow.
When the German 6th Army surrendered at Stalingrad, 91,000 survivors became prisoners of war. Of that group, approximately 85,000 died in the months immediately following their capture. Only around 6,000 survived long enough to be repatriated after the war.
According to historian Edward Peterson, the United States handed over several hundred thousand German prisoners to the Soviet Union in May 1945 as a gesture of friendship. Reports confirmed that 6,000 German officers were sent from Western camps to NKVD special camp Nr. 7, located at the former Sachsenhausen concentration camp site.
The National Committee for a Free Germany was a Soviet-organized body formed from German prisoners of war who cooperated with the Soviet Union. POWs who participated in the committee or the associated League of German Officers received improved rations and more privileges in the camps.