For (5) I’d mention a few American authors offhand. I’d definitely include Harriet Beecher Stowe is definitely one, because _Uncle Tom’s Cabin_ unleashed a great deal of feeling against slavery. When Abraham Lincoln met her, he said, “So you’re the little lady who started this great war.”
I’d also include Upton Sinclair’s _The Jungle_ since it contributed to the passage of legislation regulating food production.
More recently, I’d include Rachel Carson’s _Silent Spring_, which sparked awareness of the effects of chemicals on the environment and led to the banning of DDT and other pesticides.