Short answers, pulled from the story.
Generalplan Ost aimed to eliminate entire populations in Eastern Europe to make room for new German communities. The plan intended to create a New Order where only Germans and Aryans would remain through racial purification.
SS-Standartenführer Hans Ehlich testified that he drafted the original version alongside Konrad Meyer. Heinrich Himmler personally supervised the drafting of at least five versions between 1940 and 1943 under the Reich Security Main Office.
The plan called for the death of more than 60 million Slavic, Romanis, and Jewish people. Approximately 80 million Russians were targeted for deportation beyond the Ural Mountains with an estimated 30 million deaths during forced displacement.
Nazi planners abandoned extermination campaigns of the GPO by mid-1943 after the Battle of Stalingrad. Resources allocated to colonization policies were diverted to Axis war efforts following this defeat from spring 1943 onward.
Nearly all wartime documentation on Generalplan Ost was deliberately destroyed shortly before Germany's defeat in May 1945. Two out of three primary records associated with the plan were lost after the war though some documents emerged later like a memorandum released on the 27th of April 1943.