Explanations for all of them, again under a cut.
Ovid invented the version where Medusa was originally a woman and Ovid hated most of the gods on principle. Also, he was Roman. The earliest versions of gorgon myths depict her and her sisters as being born as monsters.
There's no reference in ancient mythology to Hestia giving up her spot. In some regions she was one of the 12 Olympians, and in others Dionysus was on the list instead. The idea that she stepped down was invented by modern writers who like to have coherent logic in their stories.
Explained above. A bit of creative writing.
Pandora according to Hesiod was the first woman and perfectly aware of what was in her jar. She was created as part of the punishment for mankind. Human women didn't exist before Pandora according to Hesiod. But because Hesiod was misogynistic even by ancient Greek standards, writers and artists after the ancient Greek religion died out re-characterized her as stupid and curious rather than evil.
5. As explained above, real.
6. This version was invented by Nathaniel Hawthorne. In the original myth, Midas just got hungry. No Daughter involved.
7. Aphrodite was worshiped as a war goddess mostly in Sparta and sort of Rome as Venus. Most Greeks weren't comfortable culturally with the idea of a goddess of love also being a goddess of war so in most of Greece she was just a goddess of love.