Short answers, pulled from the story.
The Japanese Instrument of Surrender was signed on the 2nd of September 1945. The ceremony began just after 09:00 Japan Standard Time and the surrender took effect at 9:25 a.m. JST aboard the USS Missouri in Tokyo Bay.
Foreign Minister Mamoru Shigemitsu signed for the Japanese Government at 9:04 a.m., and General Yoshijiro Umezu, Chief of the Army General Staff, signed for the Imperial General Headquarters at 9:06 a.m. Nine additional Japanese delegates were also present, drawn from the Army, Navy, and Foreign Ministry.
Nine Allied nations signed: the United States, China, the United Kingdom, the Soviet Union, Australia, Canada, France, the Netherlands, and New Zealand. General Douglas MacArthur signed first as Supreme Commander for the Allied Powers, followed by representatives of each nation in sequence.
Canadian representative Colonel Lawrence Moore Cosgrave, who was blind in one eye from a World War I injury, signed one line below his intended position on the Japanese copy. Every Allied signatory after him was displaced by one line as a result. General Richard K. Sutherland corrected the discrepancy by crossing out the printed nation titles and rewriting them by hand, then initialing each alteration.
The most significant flag on the Missouri's surrender deck was one flown by Commodore Matthew Perry in Tokyo Bay in 1853-54, when he led the U.S. Navy's Far East Squadron to force the opening of Japan's ports. It was brought from the Naval Academy Museum in its glass case. The ship's standard-issue American flags were ordinary GI-issue colors, not the Pearl Harbor White House flag as was sometimes claimed.
The Allied copy is held in the National Archives Building in Washington, D.C., formally accessioned on the 1st of October 1945. The Japanese copy is at the Diplomatic Archives of the Ministry of Foreign Affairs of Japan in Tokyo and was last publicly displayed in 2015 for the 70th anniversary of the signing.