100% (the default) is the recommended size, any other zoom level is based on personal (or medical) preferences.
Depends on your eyesight definition (mine is marginal), your viewing distance (mine varies from 8 feet to 20 inches) and what screen size you use (mine varies from 46 to 14 inches). Your situation is best judged by you, not us.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.