Vladimir Lenin came to power via a October Revolution in Russia in 1917, which brought an end to Czarist Russia and started the creation of a Communist State.
No group or person overthrew Lenin. Lenin died of natural causes in 1924 while still in power.
He was one of Lenin's right hand men in the Communist Party, he fought for power with Trotsky when Lenin died, his choice to go with 'Communism in One State' was more popular than Trotsky's World Communism leading to Trotsky's expulsion and Stalin's rise to power.
Lenin and the Bolsheviks came into power on October 26, the culmination of the two day October Revolution. Prior to that, the Russian Provisional Government was in power. Arrest warrants were out for Lenin since July, 1917 and he had to flee the country to Finland to avoid capture. He snuck back in under disguise to organize the October insurrection which brought him and the Bolsheviks into power.
Joseph Stalin along with Grigory Zinoviev and Lev Kamenev tried to take power from Lenin when Lenin was disabled by strokes. These three ran the government in Lenin's absence as he recovered and continued to do so secretly even when Lenin returned to work. The three would make governmental decisions in secret meetings after the general meetings that Lenin attended. Stalin restricted access to Lenin when Lenin was recovering. Stalin's biggest move for power was after Lenin made him Secretary General of the Communist Party. Once in that post, Stalin placed people loyal to him in many governmental offices. Stalin never did unseat Lenin, but he certainly tried and succeeded to take at least some of Lenin's powers away.
It was Russia
Yes
First Leon Trotsky, then Grigory Zinoviev and then Nikolai Bukharin lost in the power struggle after Lenin's death. All three of them and Joseph Stalin had claims to be Lenin's successor, but Stalin outmaneuvered them all.
The Germans are the ones who assisted Lenin to power. They did this with the expectation that he would undermine the Russian efforts in the war.
No, because Karl Marx was never in power in any country of government and because Marx had already died by the time Lenin was gathering his revolutionary ideology and power.
Lenin took power in the October 1917 Bolshevik Revolution, which actually took place in November 1917, but Russia was using the Julian calendar instead of the Gregorian calendar. Lenin's Bolsheviks had control of some parts of the government, but not all The Russian Civil War broke out between the Red Army (Lenin and the Bolsheviks) and the opposing White Army. The Red Army won out in 1920, placing Lenin firmly in power.
At first, lenin... then lenin died and Stalin screwed with the succession and seized power.