What other quite 'fundamental' info of that kind is out there?
You'll have to specify "fundamental" better. What are you looking for? How to stop bleeding? How to start a fire in the rain? How to build a house with no tools other than an axe? How to run a farm with no engines or fertilizer?
In the US at least there is a large community/meme/circle of "survivalists" who are preparing for life after TEOTWAWKI -- The End Of The World As We Know It. They have active forums and LOTS of information about what to do after a catastrophe.
See my edit. I know of that community as I read about them in a mixture of social and practical fascination. I ordered the info material mentioned because I was curious what my government specifically advises to do in different scenarios they deem plausible and they range from 'simple' house fires to large-scale contamination of air by biological or nuclear material.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.