1)
What is the meaning of "Machshim"?
1.
Rashi: They warned the entire nation to be quiet, and not cry more. Ibn Ezra - this is Po'el Yotzei (acts on another; they cause people to be quiet).
2)
What is the meaning of Hasu"?
1.
Rashi: It is an expression of silence, like "va'Yahas Kalev."
3)
It already said that today is Kadosh to Hashem (9-10). Why is this repeated?
1.
Malbim: Chazal said that Yom Tov should be half for Hashem, and half for you. Half the day that passed, they were Makdish it to Hashem. Now he commanded them to go to their houses to eat fatty food. The Leviyim added that also the second half is Kadosh, via Simchas ha'Chag. Therefore it says Kadosh Stam (not Kadosh la'Shem).
