No one has a gun or anything. In China you have to have a permit to have a knife over a certain length, even for kitchen knives. At least that's my understanding.
Nothing surprising about this. We (the US) actually gave immunity to German doctors post WW2 in trade for them giving us the details of their experiments on people. They did some pretty sick stuff by the way.
Good prediction, only thing I don't see is Juugo being able to give Sasuke chakra the way Naruto did. When Naruto gave out his chakra it was a pretty incredible feat.
If Oro brought them back not to their full power was Madara also not brought back full power? Imagine how strong they could be if they were full power.