1)
Why does it say "Yarad"?
1.
Rashi: The city was elevated, and Even ha'Zocheles was below in the valley.
2)
Why did he say "ha'Yom", and mention all the invitees?
1.
Malbim: It is impossible that he did so today, in the king's lifetime, and invited all of these, without the king's knowledge.