Short answers, pulled from the story.
Boris Yeltsin served as President of Russia from 1991 to 1999. He was elected president of the Russian Soviet Federative Socialist Republic on the 12th of June 1991, winning 57 percent of the popular vote, and resigned on the 31st of December 1999.
Yeltsin was instrumental in the Soviet Union's dissolution when he met Ukrainian president Leonid Kravchuk and Belarusian leader Stanislav Shushkevich in Belovezhskaya Pushcha on the 8th of December 1991. The three signed the Belovezha Accords, declaring the Soviet Union no longer existed as a subject of international law and announcing the formation of the Commonwealth of Independent States. The Council of the Republics formally voted the Soviet Union out of existence on the 26th of December 1991.
Yeltsin implemented economic shock therapy beginning on the 2nd of January 1992, liberalizing prices, foreign trade, and currency, while launching a nationwide privatization programme. Through the 1990s, Russia's GDP fell by 50 percent, hyperinflation wiped out personal savings, and tens of millions of Russians were pushed into poverty. A small group of businessmen known as oligarchs acquired controlling stakes in major state enterprises at very low prices.
Vladimir Putin succeeded Yeltsin as president of Russia. Yeltsin appointed Putin as prime minister on the 9th of August 1999 and publicly named him as his preferred successor. When Yeltsin resigned on the 31st of December 1999, Putin became acting president; his first presidential decree granted Yeltsin lifelong immunity from prosecution.
On the 21st of September 1993, Yeltsin unconstitutionally dissolved the Supreme Soviet and Congress of People's Deputies by decree. Parliament declared him removed from the presidency and swore in vice president Alexander Rutskoy as acting president. The crisis ended on the 4th of October 1993 when tanks loyal to Yeltsin shelled the parliament building, killing 187 people and wounding nearly 500 others. A referendum held in December 1993 approved a new constitution that significantly expanded presidential powers.
Boris Yeltsin died of congestive heart failure on the 23rd of April 2007, aged 76. He was buried on the 25th of April 2007 at the Novodevichy Cemetery in Moscow, following a period during which his body lay in repose at the Cathedral of Christ the Saviour. He was the first Russian head of state in 113 years to receive a church burial, after Emperor Alexander III. President Putin declared the 25th of April a national day of mourning.