Why did she say "if I found grace in your eyes"? She did not say so when she invited him to the first Mishteh (4)!
Malbim (4): That did not require grace. She merely said, if he wants to drink and eat, he should come.
Why did she say "if I found grace in your eyes" and "if it is good for the king"?
Vilna Gaon: If I have grace to grant my She'elah, and if it is good for the king to do my Bakashah for others.
Malbim: She made two conditions. (a) She is pleasing to him to grant her request due to her grace. (b) The request itself is good for the king, and not against his desire. She nullifies her desire to his.
Why did she say that she will make her request only tomorrow?
Ibn Ezra: She had not seen any sign [that Hashem decided to nullify the decree] due to the fast. On the second day, she had seen the elevation of Mordechai, so she was bold to request.
Vilna Gaon: I cannot say it now, due to my great pain. Her true intent was like the Gemara said (refer to 5:4:3:1-12). Also, perhaps it is bad in Hashem's eyes, and it will not help at all 1 . Therefore, she pushed him off until tomorrow. Perhaps she will find out that Shamayim agrees, like it was.
If Hashem does not agree to save Yisrael, what can she do? Perhaps the Vilna Gaon means that if Hashem does not agree to save us now, I will not request this now. However, what great matter would she request in place of this, for which she risked her life? (PF)
Above (4), she said "Asher Asisi Lo." Why did she say now "Asher E'eseh Lahem"?
Alshich: The first time, she said that it was for Haman (the last one mentioned before "Lo"), and the king was secondary to him. He was upset, and called her only Esther, and not Esther ha'Malkah. To fix this, now she said 'for them.'
R. Shlomo Alkavetz: She intended to arouse the king's envy of Haman; she equated him to the king. (The first time, she meant only for the king.)
Ohr Chadash (Maharal): (a) The first time, she already made the Mishteh for the king. She was unsure if he will consent that also Haman come. Now she saw that he consents, so she will make the next one for both of them. (b) The first time, Haman was not present. Now, he was; it would belittle his honor to say that she makes the Mishteh only for the king.
R. Yehonason Eivshitz: The first Mishteh was on Yom Tov. She and her servants (also they were Jewish) could not cook for her (she is fasting), nor for the king (a Nochri). She cooked only for Haman 1 (Mordechai's Eved Kena'ani). According to those who say that the first Mishteh was on the 16th, the second was on Chol ha'Mo'ed, and she could cook for both of them 2 .
R. Galiku: The first time she feared to say Lahem, lest this arouse in the king ill will against her. After his love for her was aroused at the first Mishteh, she did not fear this (and wanted to arouse envy of Haman).
Vilna Gaon: She wanted to Haman to think that he is esteemed in her eyes, just like in the eyes of the king. (Before, she did not speak in front of Haman.)
What is "ki'Dvar ha'Melech"?
Rashi: It is what you always requested from me - to reveal my nation and birthplace.
Vilna Gaon: I will tell you my requests.
Malbim: The king wants me to request. I do not consider myself worthy to request - I do so only because you want!
