Due to the isolated locations of most of the camps, military forces could not reach the death camps immediately.
The Nazis didn't want to carry out the Holocaust publicly, for example in the street.
I know of at least one, not counting the concentration camps that were turned into museums...
Yes, Hitler was the one who wanted the "Final Solution' and he was well aware of what was going on in the concentration and extermination camps.
The first document of a Jew before going to a concentration camp was Anne Frank's diary, which was published postmortem by Miep Gies and Anne's father when they unexpectedly recovered it. Elie Wiesel, a Holocaust survivor, wrote a book called "Night" describing his experiences at Auschwitz. There are many other Holocaust survivors as well, who are tell their experiences of concentration camps in museums for younger audiences.
they pretended not to know
Your question is unclear. As a many Jews were in the camps it is safe to assume that they knew of them.
After the Holocaust most people went back to their homes but instead of finding their homes their neighborhoods were destroyed. So techniquelly there is no answer to this question because we simply don't know unless we were in the holocaust ourselves.
No. Most Jews were unaware of the existence and purpose of the Concentration Camps and the Death Camps.
Auschwitz will always be known for being a Nazi concentration and extermination camp during World War II, where millions of innocent people, mostly Jews, were imprisoned, tortured, and systematically murdered. It represents the horrors of the Holocaust and serves as a symbol of the atrocities committed during that time.
No. They did not necessarily know in detail what was going on in the camps and, in any case, what could they have done? They were unarmed civilians. In any case, most of the extermination camps were in remote, rural areas. It has become oh-so-fashioable to blame 'bystanders', without asking whether they were in any position to do anything effective.
To survive in a Camp, you had to forget tomorrow, you had to forget your family, or your past. Think of NOW, nothing else, and unless you were picked for death when on a parade, or died from disease, or lack of food, you might, just might, live until tomorrow. People who thought about tomorrow, or their past, or their families, died...they just died, sometimes for no real reason such as being beaten by the guards. They died because their 'spirit' was broken. They 'thought' too much. You had to keep your spirit, your humanity, you had to accept what was going on around you, and think of NOW.