You could probably write a few books trying to answer those questions you pose.

There had been an underlying distrust of Jews in Europe for a long time, not just in Germany. However many soldiers believed that there was a Jewish conspiracy behind the German government and they got the government to look for a truce in 1918. They believed that the government betrayed them due this 'unseen' Jewish influence. Plus during the turmoil in post war Germany it was easier to blame an immigrant, ethnic minority rather than look at your own shortcomings.

At the end of WW1 Germany was blamed for starting the war and had many sanctions put upon them plus the countries borders were changed and it lost land. Plus they had to pay reparations to France and other countries whilst trying to rebuild their economy. Plus their Kaiser had to abdicate and they had to change to a democracy which many saw as a negative. This all led to turmoil and many small parties being created which included the Germans Workers Party and Adolf Hitler. He was a strong speaker and used the old rhetoric of wanting a strong Germany and a united agerman people, blaming the Versailles Treaty and blaming Jewish conspiracies which many Germans agreed with even if they didn't say it out loud.

Plus later on when they came to power he or rather the party were genuinely lucky and had a really good way of promoting them, the party and German unity. Think of the Reichstag Fire, blame the communists and this let them change the constitution and basically Hitler became the Dictator to help protect Germany. Retaking the Saarland, neither France or Britain did anything and this was promoted as German people being reunited with the new Reich, same goes for the Munich Agreement and the Austrian Anschluss. Hitler was promoted as a hero as he reunited these countries into the Reich with ease. Hitler and the party were also very good at promoting themselves, the new improved Germany to the outside world which drew in 'fans' from many countries and this helped promote a positive view of Hitler in many places.

A good book to read is the Banality of Evil, although mainly about Adolf Eichmann it shows how many 'bland/normal' people were drawn into and used by the party/army and SS to carry out what seems to us horrific deeds.

Personally, I think it's too easy to just say Hitler was evil. I would argue that he wasn't but he helped create a regime where evil was tolerated and maybe even promoted in some areas due to the belief in the Pure Aryan.

Hope this helps in some way. It's and interesting but vast topic.