Why did he show off his wealth?
Kol Eliyahu, Divrei Eliyahu: Refer to 1:3:1:1.
Malbim: He wanted to show that it is his, for his kingship is unlimited. In a limited kingship, the royal treasury is of the nation. Every king needs wealth; an awesome king must increase storehouse according to his grandeur.
What do we learn from "Yekar Tif'eres"?
Torah Temimah citing Megilah 12a: He wore Bigdei Kehunah. It says here "Tif'eres", like it says about Bigdei Kehunah "l'Chavod ul'Sif'ares" (Shemos 28:2).
Kol Eliyahu, Divrei Eliyahu: From the six words "Osher Kevod Malchuso Yekar Tif'eres Gedulaso", we learn that he showed to them six storehouses every day.
What was "Yamim Rabim"?
Rashi: The party.
What is the significance of 180 days?
Kol Eliyahu, Divrei Eliyahu: Nebuchadnetzar had 1080 storehouses; he buried them in a river. Hashem revealed them to Koresh for authorizing rebuilding the Mikdash; Achashverosh inherited them from him. He showed six every day (refer to 1:4:2:2), so it took 180 days.
Barak ha'Shachar (Vilna Gaon) Mishlei 31:30, citing Magid Meisharim (4a): When one goes to the world to come, he has 180 1 days to expound what he learned in this world, and afterwards is the Mishteh of Torah for seven days. "Shemonim u'Me'as Yom; uvi'Mlos? Mishteh Shiv'as Yamim" hints to this.
Even Shleimah (from the Vilna Gaon, 28) says 150 days. The Magihah suggests that the text should say 180. (PF)
