Short answers, pulled from the story.
Boris Berezovsky emerged as the first well-known Russian business oligarch during this period. He was a mathematician and former researcher who established his private company after working at an Academy of Sciences research centre.
Mikhail Khodorkovsky began importing computers in 1986. This activity occurred before he later acquired key assets via loans for shares auctions that took place in the run-up to the 1996 election.
The influence of Yeltsin-era oligarchs dissipated through imprisonment or emigration following Vladimir Putin's ascent to power. Mikhail Khodorkovsky was arrested in October 2003 and sentenced to nine years initially, later extended to fourteen years before release on the 20th of December 2013.
London is known as Moscow on Thames where many Russian oligarchs bought homes in upmarket sections. Roman Abramovich purchased sixteen Kensington Palace Gardens for £120 million while Mikhail Fridman restored Athlone House in London as primary residence in 2016.
The United States announced Task Force KleptoCapture in March 2022. This team included officials from FBI, Marshals Service, IRS, Postal Inspection Service, Homeland Security Investigations and Secret Service to target oligarchs directly following the invasion of Ukraine.