Short answers, pulled from the story.
By 1950, about 12 million Germans had fled or been expelled from east-central Europe into Allied-occupied Germany and Austria. The West German government put the total higher, at 14.6 million, including ethnic Germans who had settled in Nazi-conquered territories and children born to expelled parents.
The Potsdam Agreement was drafted at the Potsdam Conference held between the 17th of July and the 2nd of August 1945. Article XII recognized that the transfer of German populations remaining in Poland, Czechoslovakia, and Hungary would have to be undertaken, and stipulated that transfers should be effected in an orderly and humane manner. The agreement also redefined Central European borders and approved expulsions from former German territories transferred to Poland and the Soviet Union.
The Wilhelm Gustloff was a mobilized Strength Through Joy liner sunk in January 1945 by Soviet submarine S-13 in the Baltic Sea. About 9,000 civilians and military personnel escaping East Prussia died in the sinking, making it the largest loss of life in a single ship sinking in recorded history.
Between the 23rd of January and the 5th of May 1945, up to 250,000 Germans were evacuated to Nazi-occupied Denmark under an order issued by Hitler on the 4th of February 1945. They were interned in hundreds of camps after the war, and 13,492 German refugees died in Denmark in 1945, including 7,000 children under five. The last refugees left Denmark on the 15th of February 1949.
The West German government's official estimate of 2 million deaths was produced by studies whose lead authors included rehabilitated former Nazi party members, and which relied on incomplete cooperation from Communist governments in Eastern Europe. A 1974 German Federal Archives study, kept secret until 1989, estimated only 600,000 deaths. Historian Rudiger Overmans concluded in 1994 that more arguments support the lower figures, and some scholars now estimate the actual total at 500,000-600,000.
Rather than expelling its approximately 200,000 remaining ethnic Germans, Yugoslavia converted ethnic German villages into internment camps where over 50,000 perished from deliberate starvation and killings by guards. A total of 166,970 ethnic Germans were interned, of whom 48,447, or 29 percent, died. The camp system was shut down in March 1948.