This is the title of the book. Here "vision" is used in the general sense of a message from Yahweh, rather than to indicate how Obadiah received the message. Alternate translation: "The message of Obadiah" or "The prophesy of Obadiah"
This is the name of God that he revealed to his people in the Old Testament. See the translationWord page about Yahweh concerning how to translate this.
Here "her" refers to Edom. This is a metonym for the people of Edom, so it could also be translated as "them." (See: [[rc://en/ta/man/jit/figs-metonymy]])