Short answers, pulled from the story.
The Imperial Japanese Navy ceased to be an effective fighting force by July 1945. Only six aircraft carriers, four cruisers, and one battleship remained in somewhat working order at naval bases like Kure.
Major General Leslie R. Groves Jr. directed the Manhattan Project. The project employed hundreds of thousands of American workers at dozens of secret facilities across the United States starting from 1942.
The Potsdam Declaration announced terms for Japan's surrender stating there were no alternatives if Japan did not comply. It specified elimination of authority of those who misled people into world conquest and occupation of points designated by Allies.
The Enola Gay dropped an atomic bomb code-named Little Boy on Hiroshima on the 6th of August 1945 at 8:15 am local time. Confused reports reached Tokyo that Hiroshima had been leveled with a blinding flash and violent blast.
Emperor Hirohito made the gramophone record around 23:the 0th of August 14. Three princes dispatched the 14th of August deliver news personally to Korea, Manchuria, China Expeditionary Army, and other regions.