1)
What is the significance of "Timloch Tachas Vashti"?
1.
Vilna Gaon: Memuchan said "Re'usah" (19) - one who has lineage like her. The king's youths said Tovas Mar'eh - there is no needed for lineage 1 . Whoever it is will rule in place of Vashti. They said Vashti, and not ha'Malkah Vashti.
1
Malbim: All that is required is "she is good in the eyes of the king"!
2)
Why does it say only that it was good in the eyes of the king, and does not mention the Sarim?
1.
Malbim: The Sarim were not needed. They already gave to him power to do everything alone.