Headscratchers / YU-NO

• So I recently finished the game. The epilogue was awesome and all, but I was kind of disappointed that many questions I was expecting to be answered were apparently not - or maybe I missed/forgot the info.
  1. Who made the prank calls and why?
  2. Who was the "devil woman" that the real headmaster feared so much?
  3. Why did Takya's real mother commit suicide? In Koudai's memorandum, she talked something about not being the same - was she under Niarb or possessed by the Big Bad, or something?
  4. How exactly did the storehouse suddenly age 400 (I assume) years?
  5. The two lightning towers' behaviour seemed slightly different. The one in the other world punished any who left the area, the other killed any who tried to transport the minerals away. The latter's purpose was to protect the minerals from being mined, but the former did the opposite. What's up with this?
  6. How did Kanna get her jewel in the first place? I'd imagine she would had to have it since birth, or else she would have died. Did her mother Amanda somehow bring it with her?