Short answers, pulled from the story.
Vladimir Lenin developed a political ideology in the early 20th century that responded to specific conditions within Imperial Russia. The socio-economic landscape of this empire was characterized by combined and uneven economic development with rapid industrialization occurring within a predominantly agrarian society.
The function of the Leninist vanguard party is to provide the working classes with political consciousness and revolutionary leadership. Lenin argued that only a disciplined organization could successfully depose capitalism in the Russian Empire, as seen in What Is To Be Done? published in 1902.
In Imperialism, the Highest Stage of Capitalism published in 1916, Lenin analyzed how capitalism transformed into a global financial system where wealthy countries maintained domestic labor aristocracies. Therefore, proletarian revolutions could not occur in capitalist countries while this imperialist global-finance system remained in place, making Russia the politically weakest country in the system during the early 20th century.
Anti-Bolshevik terrorism aided White Armies counter-revolution efforts which led the Bolshevik government to ban all other political parties during this conflict. This left the Leninist vanguard party as the sole political entity in Russia despite initial soviet constitutionalism allowing competition alongside other parties.
Lenin advocated national right to self-determination among oppressed peoples within the deposed Russian Empire because he opposed Russian chauvinism and ethnocentrism. In The Right of Nations to Self-determination published in 1914, Lenin argued that acknowledging nationalism naturally allows socialist states to transcend political limitations.
After Lenin's death on the 21st of January 1924, Stalin formed ruling blocs with Grigory Zinoviev and Lev Kamenev then Nikolai Bukharin who determined soviet government policy from 1924 onwards. Trotsky ideologically battled Stalin while factions including Leon Trotsky and Stalin fought for control over the Communist Party.