When we request each other to provide evidence in an argument, should we be referring to source papers that contain original data, or is referring to authorities good enough?
If it's good enough, when and why is that the case?
No reference is so good as to be unquestionable. In fact citing references is only the start of a discussion. There is also verifying that a proponent is correct about the reference, verifying that the reference is relevant, and then verifying that the reference is correct.
Papers with data, at least to the point that we understand the data, are more easy to verify, but it is equally important that the reasoning and implications based on the data are correct.
As to your last question, I don't think limiting the conclusions to what is generally agreed on is a useful technique for a debate site. What is wanted is a chain of fact and assertion that is logically rigorous and based on the truth and the strength of that chain is what we want to discuss here.
Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846)
I have never met a man so ignorant that I couldn't learn something from him. Galileo Galilei
If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass