Far from being a staunch ally the Soviets were simply allies because Germany decided to invade.
Stalin was responsible for WWII beginning. Germany was scared to start a 2 front war in 1939 because Germany was not on a footing to fight such a war. The USSR formed a secret non-aggression pact with Germany. In 1941 came the invasion of the USSR and that event is what caused the USSR to change sides. It was because the Nazis invaded the USSR otherwise the Soviets would simply have stayed secret partners with the Nazis.
To suggest that the USSR was responsible for WW2 takes American anti-communism to new depths! Even Churchill never claimed what you have, and he was certainly no fan of communism!
In the 1930s the USSR recognised the increasing threat arising from Hitler's expansionist vision. The Soviet government and people were bitterly hostile topwards the Nazis. The communists in Germany were the first group to be persecuted by the Nazis, with its leading members sent to concentration camps and the Communist Party itself brutally suppressed. The USSR was ill prepared for war. It tried repeatedly to negotiate defence treaties with Britain and France but was rejected. In order to buy time the non aggression pact with Germany was signed. The Soviet government had no illusions that this would last, they knew (because Hitler had made it no secret) that sooner of later the Nazis would attempt to annexe large parts of the Soviet Union. The period between the signing of the treaty and the invasition of the USSR was used to enable a massive rearmament programme to be undertaken. It also enabled much heavy industry to be moved to greater safety beyond the Urals.
The Soviet government were taken by surprise by the invasion on 22nd June 1941, but only because they thought it would take place later. Of course that resulted in the USSR joining the war and becoming allies with the UK and the Commonwealth countries. At that time of course the USA was not involved. It was neutral. It entered the war against Japan as a result of the attack on Pearl Harbor on 7th December 1941. It only entered the war against Germany following Hitler's declaration of war against the USA on 11th December 1941. There was of course a very strong isolationist trend in the USA, which only changed as a result of Pearl Harbor.
That is enough for one post. I will challenge the rest of the garbage in your post later.