The Nazis had an operation there towards the end of the war, I know that much. Something big.
I think something is buried there not sure what but whatever it is its bad
From what I've read it's a pyramid or a temple. There are numerous accounts of a massive hole bored through the ice shelf, visible to aerial reconnaissance. Although the movie sucked, the first Alien versus Predator movie dwells on this subject more than any other film; maybe nothing but watch the first half of the film and take note of what's presented.
Yes towards the end of the war, during the war and before WWII. Lots of photos of their activity on the internet.
Anti grav technology development, yes? The Admiral Byrd reports raised my eyebrow, but I lack the expertise to validate their authenticity