What do we learn from "va'Yhi"?
Megilah 10b: We have a tradition from Anshei Keneses ha'Gedolah that 'va'Yhi bi'Ymei' always denotes pain. In the days of Achashverosh there was Haman.
Megilah 11a: We read this Vai v'Hai (woe and mourning). "You will be sold to your enemies for slaves [and no one will buy]" (Devarim 28:68) was fulfilled. (Haman's decree did not allow Yisraelim to be kept alive for slaves.)
What was Achashverosh's nation, and when did he rule?
Rashi: He was Melech Paras. He ruled after Koresh at the end of the 70 years of Galus Bavel.
What is the significance of the name Achashverosh?
Megilah 11a #1: He is Achiv Shel Rosh, the equal of Nevuchadnetzar ha'Rasha, who was called Rosh - "Ant Hu Reishah Di Dahava" (Daniel 2:38). He has the same Mazel as him. Nevuchadnetzar killed, and destroyed (the Mikdash), Achashverosh sought to do the same.
Megilah 11a #2: In his days Hushcharu (were blackened) the faces of Yisrael like the bottom of a pot.
Megilah 11a #3: Anyone who recalls him says 'Ach l'Rosho' (gets a headache).
Megilah 11a #4: All were made Rashin (poor) in his days - "Achashverosh imposed a tax?" (10:1).
Why does it add "Hu Achashverosh"?
Rashi citing Megilah 11a: He was evil from his beginning to his end.
Vilna Gaon: There was a previous Melech Achashverosh, Daryavesh's father (Daniel 9:1), who ruled only over Paras and Madai. This one ruled over the entire world.
What do we learn from "ha'Molech"?
Rashi citing Megilah 11a: He made himself king 1 (he was not from the seed of the kingship). Malbim - he was initially a commoner; via his wealth 2 , he ruled over Madai u'Faras and strengthened his kingship, until he ruled by force over 127 nations. If one conquers by force and makes himself king, e.g. Nimrod, his kingship is unlimited. Normally if a nation chose a king, they limit his kingship in five ways. 3 A king such as Sancheriv or Nebuchadnetzar was not limited; all were considered his slaves, to do with them as he pleases. To solidify his kingship, Achashverosh married Vashti, Nebuchadnetzar's granddaughter, who was the heir to the kingship. From this aspect, his kingship would be limited. 4 Initially they accepted him as an heir, to have a limited kingship. He wanted an unlimited kingship, so he moved the capitol and ordered Vashti to come to him (refer to 1:2:3:2, 1:11:1:1, 1:11:2:1).
11a: Some explain this to his credit, i.e. there was no one else as fitting as him to be king. Some explain this to his detriment, i.e. he was not fitting to be king. He gave much money (to nobles and dignitaries) and became king.
Initially, he guarded the king's horses! However, we find that the overseer of Rebbi's horses was exceedingly rich (Shabbos 113b). (PF)
Malbim: (a) He must swear to guard the nation's code and etiquette. He guards the country. He is their head to enforce their laws, fight their wars and manage all their affairs. They are obligated to do only what is needed for the Klal, e.g. to pay taxes. (b) A limited king does not own the royal treasury; it is of the nation. (c) He cannot do a matter of the Klal without the advisors' consent. (d) The first [limited] king cannot make new laws, but the second king can. (e) Refer to 1:2:3:2.
Why is an inherited kingship limited? Is it because he was not the heir, just he married the heir? It is better to say that it is because Vashti 'inherited' Malchus Bavel, and Paras and Madai seized the kingship from Bavel.
What is the significance of "from Hodu until Kush"?
Megilah 11a #1: These are at opposite ends of the world.
Rashi, citing Megilah 11a #2: They are next to each other 1 . Just like he ruled over them, so he ruled from one end of the world to the other end 2 . Ohr Chodosh - people feared him as if his capital was nearby. The first opinion agrees that Hodu and Kush are adjacent. The entire world is between them, i.e. if one goes around the world from one to the other.
Malbim: It does not say that initially he ruled in Ploni, and afterwards, over 127 Medinos. He did not increase gradually. Rather, when he was still a commoner, he suddenly ruled over all of them.
R. David Kahn (Yated Ne'eman 5771 29, Musaf Shabbos p.4-5): There is a place called Kush near India and Shushan, aside from the Kush in Africa. This resolves several difficulties (refer to Shemos 7:27:151:1*). Rav and Shmuel argue about which Kush our verse discusses. Both agree that when they sent letters "me'Hodu v'Ad Kush" (8:9), It is the Kush in Africa, at the opposite end of the world.
Rashi: This is like "Ki Hu Rodeh b'Chol Ever ha'Nahar mi'Tifsach v'Ad Azah" (Melachim I, 5:4).
What is the significance of "Sheva v'Esrim u'Me'ah Medinah"?
Bereishis Rabah (No'ach DH Me'ah Shanah): In the Zechus of Sarah, who lived 127 year, Esther [later] ruled over 127 Medinos. Vilna Gaon - Medinah is a big walled city, with [nearby] open cities.
Kol Eliyahu citing a Midrash: He had 100 provinces on the land, and 27 on the seas. A support is "Mas Al ha'Aretz v'Iyei ha'Yam" (10:1) - the Gematriya of Mas is 100 (these were Al ha'Aretz); the Gematriya of v'Iyei is 27 (they were on ha'Yam).