In general, the Evangelion mangas are considered good. They expand on the anime's universe, providing more depth and character development. However, it depends on personal preferences as some might find the style or pacing not to their liking.
Well, it's difficult to determine. Maybe it's based on real events but with some exaggerations or modifications. Or it could be completely made up. We need more details to know for sure.
The Evangelion manga is typically regarded as canon. It expands on and adds details to the overall narrative, while remaining consistent with the core concepts and characters of the franchise.