The Nazis made a list of people they wanted to exterminate. These are:
Jews
Homosexuals
Blacks and Asians
Communists
Hitler's Enemies
Criminals
Foreign spies
Political opponents/non-Nazi
People who have mental illnesses
Physically Disabled people
Roma (gypsies)
Beggars
The nazis would take them and execute them if they were lucky. If they didn't strike luck they would be left in confinement to die.
Usually children under 15 were gassed soon after arrival. The Nazis had no use for them.
If they had left the annexe they would have run the risk of being caught.
The top echelon used planes for longer distances and cars for shorter distances, most would use trains. The Nazis used more horses than any modern army and sometimes they would use trucks.
There's plenty of guilt to go around for that, but if you have to bring it down to one person most responsible for carrying it out, it would be Heinrich Himmler.
They were killed Nazis would kill anyone who doesnt fit the nazi aryan race such as Jews Polish, POWs etc.
it turned many nations who would have aided the Nazis into nations who resisted them.
The Nazis would kill him/her on the spot.
It would have made no difference in this case.The Nazis absolutely loathed international organizations as a matter of principle (unless they could be manipulated).The world was at war and the areas where the Holocaust was taking place was not accessible to the outside world.
It would be best if you had a prefered angle to come from: The Nazis: Were ordinary soldiers forced to perpetrate the Holocaust? The Victims: Did the Jews of occupied countries think that their governments would save them? The Allies: Why were there not more relief efforts to save the survivors after liberation? Reflection: Did the rise in Holocaust denial in the 70's and 80's lead to an increace in Holocaust research? obviously it depends on what level you are at.
by work, by starving, by disease
They felt confused why would the Nazis do this to innocent people. some felt angered too.