Short answers, pulled from the story.
The 1991 Russian presidential election took place on the 12th of June 1991. This date was set as a provisional timeline before any official schedule existed and followed a referendum held on the 14th of March 1991 to create the office of president.
Boris Yeltsin won the 1991 Russian presidential election with 58.6% of total cast ballots. Official results certified on the 19th of June confirmed his decisive victory which allowed him to avoid a second round runoff.
Any citizen between ages 35 and 65 could run for president under rules passed on the 24th of April 1991. Candidates needed either 100,000 voter signatures or support from 25% of Congress members to register for the race.
Nine total contenders entered the race including Boris Yeltsin, Nikolai Ryzhkov, Vladimir Zhirinovsky, Albert Makashov, Aman Tuleyev, and Vadim Bakatin. Nikolai Ryzhkov stood as the only official Communist Party nominee among four communist candidates while Yeltsin ran as an independent supported by Democratic Russia.
Tatarstan Supreme Soviet declared non-participation on the 28th of May following weeks of public protests regarding sovereignty disputes against the federal election. Bashkortostan encouraged boycotts through the Movement for a Sovereign Bashkortistan group which viewed the presidential vote as infringing upon local claims to autonomy.