Answer:
1) You can call the helpers, nazi helpers its simply up to you. Most of the people in germany saw nothing wrong as they got brainwashed with propaganda etc..
2) Several things needed to happend for the holocaust to happend. First of all you needed people to believe it was the jews fault. Second you needed people to help the nazis do this stuff, like collecting people and their belongings, so you could say the Nazis as an organization and the public all thought the same of the jews.
3) The picture could raise questions on why the arent doing anything etc..