(1) Should this debate even be allowed in the first place, or should people questioning or even probing deeper into the history of the Holocaust be jailed as Holocaust Deniers, as they are in some European countries?
No one should be put in jail for doing something that causes no harm to anyone else. Period.
This "debate" however, is not one, the Holocaust is one of the most researched events in human history and no reasonable person can even claim to have evidence refuting it because there is none. And when people ignore you, or call you crazy because you want to discuss this with them its because you have not gone through the effort of checking on the evidence yourself . The rest of us are not here to bring you out of your willful ignorance. We ignore you in the same way people ignore the homeless. One, because we know we can't do anything to really help you, and Two, because you should be helping yourself.
(2) What were the intentions of the German government in putting the Jews (and other groups) in concentration camps? Was it their original intention to kill them all? Did they offer them as bargaining chips in negotiations with the Allies?
The german government and the german people were generally not aware of the lengths the nazi leadership would go to at first. However as the system progressed almost every arm of the state and even regular societal institutions such as churches became complicit. As for direct planning yes, there are numerous sources quoting hitler as talking about it specifically and the upper leadership deliberately putting the death state together. Ovens don't pop up out of nowhere.
(3) How many Jews died and of what cause - how many were gassed alive in the camps, and how many died of disease, hunger, Allied bombing, were killed outside the camps, etc. Will the "Hitler killed 6 million Jews" claim stand an unbiased historical analysis?
It is hard to estimate how many people were killed because of the chaos of the war, the intentional coverup, and other factors. The 6 million number is a good guess that will unfortunately never be able to be completely verified. The death camps were used to kill around 3 million people, mobile death squads known as Einsatzgruppen roamed the eastern territories and killed hundreds of thousands. Victims were forced into ghettos where they died from disease and malnutrition. Medical experiments were performed on various groups. Many victims worked themselves to death in labor camps as well. These events are irrefutable.
(4) Did the victorious Allies, especially the Soviet Union, take any liberties with truth in propagandizing the Holocaust to the world? It is known that some initial claims (an eight-digit figure of dead Jews, human soap and leather, etc) had to be withdrawn in light of new evidence, and it was revealed that at least some Soviet and independent Polish massacres were blamed on the Germans. Given the history of "antisemitism" in Russia / Ukraine / Belarus / Poland (ex the Kielce pogrom in 1946), could those revelations be a tip of a much bigger iceberg?
Not really. What new evidence are you talking about? There has been a huge influx of new documents to study since the fall of the Soviet Union but the fundamentals of the holocaust have not changed because it happened as the historical record shows. Just because one massacre was committed by the Soviets instead of the Germans does not mean the Holocaust never happened.