Short answers, pulled from the story.
The Russian Constitution of 1906 established a bicameral parliament composed of the State Council and the State Duma following the Revolution of 1905. This document promised an elected parliament called the Duma without whose approval no laws would be enacted.
Nicholas II issued the October Manifesto on the 17th of October 1905 to save the monarchy after Count Sergei Witte proposed basic civil rights. This document served as the basis for the new constitution drafted by Peter Kharitonov.
Chapter One declared that the emperor possessed supreme sovereign power mandated by God himself under Article 4 while retaining an absolute veto over all legislation. The Tsar held sole power to declare war, make peace, negotiate treaties, and maintain charge over Russia's administrative affairs alongside supreme command of the armed forces.
Nicholas dismissed the First and Second Dumas when they proved unsatisfactory to him through a Ukase dated the 3rd of June 1907. The Tsar unilaterally altered election statutes in violation of the constitution to ensure more landed persons would be elected which damaged his reputation among Russian liberals.
Alexander Kerensky unilaterally abolished the Russian monarchy on the 1st of September 1917 which formally abrogated the 1906 Constitution. This act ended the imperial system entirely before the Bolshevik party took over Russia in November.