Short answers, pulled from the story.
The Belovezha Accords were signed on the 8th of December 1991 at a state dacha near Viskuli in Belovezhskaya Pushcha, a forest in Belarus. The dacha had previously served as a hunting lodge for General Secretary Brezhnev.
Six leaders signed the Belovezha Accords: Belarusian Parliament chairman Stanislav Shushkevich and Prime Minister Vyacheslav Kebich, Russian president Boris Yeltsin and First Deputy Prime Minister Gennady Burbulis, and Ukrainian president Leonid Kravchuk and Prime Minister Vitold Fokin.
The three leaders used the 1922 Treaty on the Creation of the USSR together with the 1969 Vienna Convention on the Law of Treaties. As three of the four original signatories of the 1922 treaty, they claimed standing to dissolve it; the fourth original signatory, the Transcaucasian SFSR, had been dissolved in 1936.
Gorbachev publicly declared the dissolution illegal, arguing that the fate of a multinational state could not be determined by three republic leaders and must involve all sovereign states and their citizens. He eventually accepted the outcome in a private meeting with Yeltsin three days after the Alma-Ata Protocol was signed on the 21st of December 1991, and resigned on the 25th of December 1991.
On the 25th of December 1991, Russian president Yeltsin wrote to UN Secretary-General Javier Perez de Cuellar requesting that Russia be recognized as the Soviet Union's successor state. No member state objected, and Russia retained the Soviet Union's permanent Security Council seat. Yeltsin personally occupied the seat at a Security Council meeting on the 31st of January 1992.
The original Belovezha Accords document went missing. Stanislav Shushkevich, one of the signatories, was informed by Belarus's foreign ministry on the 7th of February 2013 that the original accords could not be located. He had been seeking the document to assist in writing his memoirs.