What is the meaning of "Kol Asher Karahu"?
Torah Temimah citing Esther Rabah: [Haman] is the descendant of [Amalek] "Asher Karcha ba'Derech" (Devarim 25:18).
Vilna Gaon, Malbim: This came via Mordechai not bowing 1 .
Even though it was due to Yisrael bowing to the image, or benefit from the party (Megilah 12a), it came via Mordechai not bowing (PF). Similarly, Galus was already decreed at Bris Bein ha'Besarim, but it came via the special robe that Yakov gave to Yosef (Megilah 16b).
What is the significance of "Parashas ha'Kesef"?
Vilna Gaon: He told Hasach to tell her that the edict was to eradicate the Jews.
Chomas Anach citing Mahari: Haman gave the 10,000 Kikarim to Tzedakah. Mordechai told Esther not to fear [Haman's merit]. Haman is Mordechai's Eved Kena'ani; his money is Mordechai's (it is Mordechai's merit)! Further, it is no Tzedakah to eradicate an entire nation! Therefore, she should not fear to go to the king.
Malbim: The Kesef that Haman said to give, it had two Perushim. He told Achashverosh that those who will do the work will give this amount, amidst Simchah to do it. Haman intended that from the booty, the king will receive a tax of 10,000 Kikarim.