Short answers, pulled from the story.
The Einsatzstab Reichsleiter Rosenberg Taskforce, or ERR, was formed in 1940 and headed by Alfred Rosenberg. Hermann Göring controlled the ERR and issued orders to seize Jewish art collections and other objects.
The most notorious auction of Nazi looted art took place on the 30th of June 1939 at the Grand Hotel National in Lucerne, Switzerland. The artworks were deaccessioned from German museums and sold by Theodor Fischer.
The value of plunder taken from Eastern Europe is estimated at 4 billion Reichsmarks. This figure includes cereals, fodder, potatoes, meats, pigs, and sheep seized by Nazi forces during Operation Barbarossa.
The Allies stored recovered artworks in collecting points such as the Central Collection Point in Munich. They also used salt mines and caves like those in Merkers, Altaussee, and Siegen for protection before the war ended.
Approximately 20 percent of the art in Europe was looted by the Nazis, with well over 100,000 items remaining unreturned to their rightful owners. Many missing items include everyday objects such as china, crystal, or silver.