Short answers, pulled from the story.
Count Sergei Witte became the first person to hold this new title when Emperor Nicholas II signed a decree creating the Council of ministers. This document transformed the head of government from an emperor into a distinct role known as Chairman of the Council of Ministers.
Vladimir Lenin chaired the Council of People's Commissars from 1917 to 1924 during the reign of the RSFSR. The position existed for twelve years until the February Revolution of March 1917 ended the imperial system before this period began.
The current form of the office was established on the 12th of December 1993 following the introduction of a new constitution. Boris Yeltsin served as Head of Government from the 16th of May 1992 until he became President later that year and Viktor Chernomyrdin took office on the 14th of December 1992 after the Supreme Soviet refused to approve Yegor Gaidar.
Mikhail Mishustin received 383 yes votes out of 449 total deputies when confirmation votes occurred on the 16th of January 2020. The State Duma must discuss presidential nominations within two weeks before making a decision regarding these appointments.
The term of office for the prime minister increased to six years after constitutional amendments passed in 2012. Acting presidents cannot dissolve the State Duma or propose amendments to the Constitution during this period.