What is the Chidush that he should hear what Hashem tells him?
Malbim: Do not learn from the nation's deeds.
What is the meaning of "Al Tehi Meri"?
Rashi: Do not refuse my mission.
Radak: "Meri" is an adjective (do not be rebellious). The note Tarcha 1 changed the Sheva [under the Mem] to a Segol, like a note that breaks (from what follows it); it does so sometimes.
We call this Tipecha. (PF)
What is the meaning of "Petze"?
Rashi: Open. This is like "Patzu Aleinu Pihem" (Eichah 3:46).
What did He tell him to eat?
Rashi: This is a Mashal. Tilt your ear and hear, and it will be pleasant for you, as if you eat a food with appetite.
Radak: He should eat the Megilah (3:1), and so he did in the prophetic vision. This is a Mashal for learning words of Nevu'ah, and remembering them.
Radak citing Targum Yonasan: Extend your Nefesh and receive what I give to you.
Malbim: This is a metaphor. Hashem's word should become a Kinyan that will cling in his Nefesh, just like food becomes part of the body that eats it.
What does Hashem give to him?
Rashi: The Megilah.