This is the type of movement I've been looking forward to. I still visit Reddit but not for Reddit's sake. I go for the high quality subs with tight moderation and good content that are still on Reddit. Once they move out, there's no reason to stay on.
Hashtags are your friend. It also helps if you have some active posters for the tag. I get good content from following #sciencefiction #coffee and #python.
Five years is too generous, I think. At the end of the day, Reddit is just a forum and forums aren't profitable. Unlike the time of the Digg migration, the technology and platform have been commoditized.
I just use a French press. My current ratio is 30 grams of coffee grounds to 500ml of water. Mix together, place in the fridge overnight or about 8 hours. Transfer to teapot the following morning so as not to oversteep. Still experimenting though so I'm also curious about other techniques.
Project Gutenberg has a pretty good science fiction selection, quite extensive in fact that I think it's better to go by author than by individual works.
For the "classics" there's H.G. Wells and Edgar Rice Burroughs, aside from Verne and Shelley whom you've already mentioned.
There are some surprising names, too, like Jack London, E.M. Forster, and Rudyard Kipling.
For golden age scifi: Frederic Brown, E.E. "Doc" Smith, CM Kornbluth, Jack Williamson, Frederic Pohl, Olaf Stapledon, and Andre Norton. Also, Robert E. Howard and H.P. Lovecraft.
For your criteria, though, I would recommend looking for the works of Philip K. Dick and H. Beam Piper.
Just wanted to say thank you for setting up and running these services. The Internet is exciting again. More power to you and the team!