1)
What is the significance of giving the horse via an officer?
1.
Vilna Gaon: The custom was, when they harness the horse for the king to ride on it, the officer gives the horse to the slave who will harness it. Also this should be done for the man to be honored!
2)
The king said that one of the officers will give the attire and horse. Why are "Hilbishu", "v'Hirkivu" and "v'Kar'u" plural?
1.
Vilna Gaon: The king's servants will do this, and not the officer.
2.
Malbim: Haman wanted to increase his honor, so he said that many great officers should do these.
3)
Why did he not mention the crown?
1.
Refer to 6:8:2:1-3.