I'll take a shot at answering #2. For #2, the short version is that virtually every soldier, especially on the Eastern Front, was aware of the crimes being committed. The war aims for the Eastern Front were intrinsically linked to Nazi ideology. It cannot be understood outside of the lens of Nazi racial hierarchy, with Aryan 'clean' races subjugating 'inferior' races. As such, the way the entire war was conducted from top to bottom in the east was not as a traditional war of army versus army, combatants fighting over territory - but as army versus people groups.

Let's look at what the German Army believed prior to the invasion of Poland. Hitler said of Poland to his staff, "Our strength lies in our speed and our brutality. Genghis Khan hunted millions of women and children to their deaths, consciously and with a joyous heart. History sees in him only the great founder of a state" and that "hard ethnic struggle that will not permit any legal restrictions. The methods will not be compatible with our normal principles." Franz Halder, the chief of staff, is quoted as saying prior to the invasion of Poland 'it's the aim of the Leader and of Goring to annihilate and exterminate the Polish people'. Brauchitsch, the commander in chief of the German Army in 1939, "confirmed that the policy was to 'prevent the Polish intelligentsia from building itself up to become a new leadership stratum. The low standard of living will be maintained. Cheap slaves. All the rabble must be cleared out of German territory.' As noted by John Wheeler-Bennett, after a pogrom against German Jews in 1938, "...among the Generals there was scarcely a voice raised in protestation.' The German High Command were clearly aware of the war being fought against people and not against an army. Indeed, as John Wheeler-Bennett says: "No man who participated in the Fuhrer Conferences of August 22, 1939, and there were present the highest ranking officers of the three services, could thereafter plead ignorance of the fact that Hitler had laid bare his every depth of infamy before them, and they had raised no voice in protest either then or later."

During the invasion of Poland, activities against civilians were not limited to only SS rearguard actions. From 'The Nemesis of Power':

With the Polish war not two weeks old, yet clearly won, Ribbentrop conveyed to Keitel in the Headquarters train on September 12 the Fuhrer's instructions for the solution of the Polish problem. These included the mass execution of the intelligentsia, the nobility and the clergy of all elements, in fact, who might be regarded as leaders of a potential subsequent resistance movement — and a wholesale massacre of the Jews, the raison d'etre for which was to be a faked uprising in the Galician Ukraine. Keitel passed these instructions on to Canaris, and the ‘little Admiral was aghast. He protested that the military honour of Germany would be indelibly sullied if it condoned such crimes. But Keitel replied imperturbably that the Fuhrer had commanded these things to be done and had added, moreover, that if the Army should express disagreement with them, they would have to accept the presence as equals of units from the SS and the SIPO (Security Police), who would not scruple to do the Fuhrer's commands and who would operate independently of military government.

Of the invasion of the Soviet Union, Colonel-General Hoepner wrote: "This struggle must have as its aim the demolition of present Russia and must therefore be conducted with unprecedented severity. Both the planning and the execution of every battle must be dictated by an iron will to bring about a merciless, total annihilation of the enemy. Particularly no mercy should be shown toward the carriers of the present Russian-Bolshevik system." Von Reichenau, commander of the 6th Army, wrote: "Thereby the troops too have tasks, which go beyond the conventional unilateral soldierly tradition [Soldatentum]. In the East the soldier is not only a fighter according to the rules of warfare, but also a carrier of an inexorable racial conception [volkischen Idee] and the avenger of all the bestialities which have been committed against the Germans and related races."

It cannot be interpreted any other way than that the commanders of the Wehrmacht, in addition to the SS, conceived of the war not as a war against an army, but as a war against peoples.