Short answers, pulled from the story.
The Red Army was established by decree of the Council of People's Commissars on the 15th of January 1918 (Old Style), based on the existing Red Guard. the 23rd of February 1918 marked the first mass draft in Petrograd and Moscow and the first combat action, which became Soviet Army Day.
Leon Trotsky is credited as the founder of the Red Army. He served as People's Commissar for War from 1918 to 1924 and oversaw the transformation of the force from a voluntary formation into a conscript army with a professional officer structure.
The Soviet Armed Forces suffered a net total of 8,668,400 losses during the German-Soviet War: 6,329,600 killed in action, 555,400 deaths from disease, and 4,559,000 missing or captured, after accounting for those who returned from liberated territory or German captivity. Ethnic Russians accounted for 5,756,000 of those dead.
The Purges of the Red Army cadres in the late 1930s removed 3 of 5 marshals, 13 of 15 army-level generals, 8 of 9 admirals, 50 of 57 army corps generals, 154 of 186 division generals, all 16 army commissars, and 25 of 28 army corps commissars. The purge devastated experienced leadership precisely as the army tripled in size between 1937 and June 1941.
The Politburo authorized only a limited contingent averaging 80,000 to 100,000 troops, which was insufficient to control the Afghan countryside or secure the border. Mujahideen fighters used hit-and-run tactics with easy escape routes and supply lines from Pakistan and China, funded by billions of dollars from the United States, Saudi Arabia, and other countries.
Following the August 1991 coup attempt, the Soviet republics began declaring independence. On the 8th of December 1991, the presidents of Russia, Belarus, and Ukraine dissolved the Soviet Union and signed the Commonwealth of Independent States into existence. The last vestiges of the Soviet command structure were dissolved in June 1993, with assets divided among the successor states largely on a regional basis.