Day in the Life of Ivan Denisovich
Why don't the workers rebel against the guards if there are more workers that are poorly treated than guards?
I believe there was no point in fighting the guards, and trying to escape. Even if they did, how would they be able to survive outside alone. They also don't fight because they don't even know where in Siberia they are in. What if they left and went in a wrong direction and ended up freezing to death? Not only that, but if the people were to fight the guards and take food, people would not send any more food to the camp to prevent the violence. They would be literally killing themselves.
Why, if the prisoners are building a structure in the camp, make a secret exit to get out of some point?
Again as I said before, even if they were able to escape, where would they go? What would they eat, and how would they keep warm? Anyways, remember there is a guard tower watching over the construction, and although they don't stop you for stealing a material, as said in the book, but they will stop you if you tamper with the design of the structure.
Why are there squad leaders?
There is really no point to squad leaders aside from the fact that they organize their squad pretty well without the use of guards. They might also be their to motivate normal workers that if they do a well enough job, they can become leaders and receive an extra serving of food without having to work as much as usual. Basically, it organizes and semi-motivates workers into doing their job.
Why were soldiers from war sent to the camps?
By this I mean why would soldiers from war, who were in the Russian army, and escaped a german prison and went to Russia would be arrested. I believe that they would be arrested because the government thinks that they simply fled from the Russian army to prevent from dying. Not only that, but they would be demotivated to look for any clues of the soldier's story of being true due to the fact that they were in a war, and they needed for people to get materials for the war which is why they needed people to work unpaid.