Short answers, pulled from the story.
The federal law On Citizenship of the Russian Federation came into force on the 1st of July 2002. This statute replaced decades of imperial and Soviet regulations with a single codified system for determining who holds citizenship.
Citizenship is the status given to an individual indicating the state which exercises jurisdiction over that particular person while nationality refers to a person's ethnic group within the same legal framework. In the Russian context, these two terms are not interchangeable and cannot be used as a synonym for the other.
Provincial governments held wide discretion in determining who could be naturalized as Russian subjects until the 10th of February 1864 when the imperial government introduced a five-year residence requirement. That reform shifted authority over naturalization from provincial authorities to the Ministry of Internal Affairs of the Russian Empire.
Former Soviet citizens who were permanently resident in Russia on the 6th of February 1992 automatically became Russian citizens unless they explicitly applied to refuse citizenship by the 6th of February 1993. Residence was based on a person's officially listed place of domicile in the propiska system.
Foreign nationals may become citizens by admission after meeting a minimum residence requirement usually five years while proving a legal source of income and demonstrating proficiency in the Russian language. The residence requirement is reduced to one year for individuals who have been granted asylum or refugee status.