Short answers, pulled from the story.
A commission set up by the West German government found that 1,094,250 German military personnel died in captivity out of 3,060,000 taken prisoner. Rüdiger Overmans confirms that deaths of 363,000 POWs can be verified through Deutsche Dienststelle files.
The last prisoners returned from the USSR in 1956 following intervention by West German Chancellor Konrad Adenauer in Moscow. Most surviving POWs had been released by 1950 with only those convicted as war criminals held until this final date.
Edward Peterson states that the U.S. chose to transfer several hundred thousand German prisoners to the Soviet Union in May 1945 as a gesture of friendship. This decision created a significant number of additional deaths among those transferred to Soviet custody despite their preference for surrendering to American forces.
Soviet Ministry for the Interior documents released in 1990 listed 6,680 inmates in NKVD special camps who were transferred to Soviet POW camps. Six thousand German officers were sent from the West to the Sachsenhausen concentration camp one of these special camps before being moved to POW camps.
Ninety-one thousand survivors became prisoners of war after the German 6th Army surrendered at Stalingrad in early 1943. The BBC put the number of POW captured at Stalingrad at 91,000 of whom only approximately six thousand survived to be repatriated after the war.