Short answers, pulled from the story.
Muhammad Ali Jinnah set the date for Direct Action Day as the 16th of August 1946. This announcement followed his decision to rescind approval of the Cabinet Mission Plan on the 29th of July.
Estimates of attendance varied wildly from 30,000 according to a Central Intelligence Officer's reporter to 500,000 according to a Special Branch Inspector. The death toll of labourers residing in the mills at Kesoram Cotton Mills was reported to be between 7,000 and 10,000.
Jawaharlal Nehru held a press conference in Bombay that shattered hopes for a united India because he declared that the Congress party reserved the right to modify the Cabinet Mission Plan as it saw fit. This statement effectively rejected the idea that provinces would be obliged to join a group within the proposed three-tier structure.
After independence the Muslim population came down to 601,817 due to the migration of 500,000 Muslims from Calcutta to East Pakistan. Around 320,000 Hindus from East Pakistan migrated to Calcutta alone between 1946 and 1950 while the Hindu percentage rose from 73% in 1941 to 84% in 1951.
An important sequel occurred in October 1946 when a massacre in Noakhali and Tipperah districts erupted following news of the Great Calcutta Riot. A devastating riot rocked Bihar towards the end of 1946 between the 30th of October and the 7th of November with severe violence breaking out in Chhapra and Saran district.