Short answers, pulled from the story.
Nikita Khrushchev delivered the Secret Speech on the 25th of February 1956. The speech began shortly after midnight and continued for four hours before stunned delegates.
The Pospelov Commission investigated repressions from 1934 and found that over one-and-a-half million individuals were arrested during the Great Purge in 1937 and 1938. More than 680,500 of these victims were executed while most were long-time members of the Communist Party.
Official records state fifteen people were killed and fifty-four injured or wounded during the events between the 4th and the 10th of March 1956. Historians consider these figures highly suspect and believe hundreds may have been killed and wounded instead.
Polish October and the Hungarian Revolution of 1956 emerged as notable uprisings after Nikita Khrushchev delivered his speech. Both governments faced unpopular Stalinist leadership when de-Stalinization policies spread through the Secret Speech.
Western historians criticized the speech for appearing designed to determine Nikita Khrushchev's political fate rather than address systemic issues. Critics like J. Arch Getty argued that revelations were almost entirely self-serving and failed to explain how a bloodthirsty paranoiac could exercise unlimited despotic power over two hundred million inhabitants for twenty-five years.