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Yes, except all the information you seek is inside the great Wikipedia.
Depends on the subject matter. The less popular subject matters still should be read in books.
And academic journals
Depends on how "popular" of a subject it is. There are plenty of subjects on Wikipedia that are not popular enough to have ever been published about in print.
I guess that's the other side of the coin. I'm a Mesoamerican history nerd and a lot of the articles on Wiki are sparse at best on the subject or outright misinformation (repeated misinformation I see almost verbatim copied and pasted). I see your point though, without an easy way of archiving information a lot of subjects would and have fallen through the cracks in humanity's notice.
I don't know about all the information, but I'd rather read Wikipedia about a historical event than watch a YouTube about it