What is "Ulefu"?
Rashi: It is an expression of fainting, like "Tis'alafnah ha'Besulos
What is the comparison to Toa Michmar?
Rashi: It is Hefker like this Toa fell into a net. Toa is one of the seven Kosher Chayos - "u'Se'o va'Zamer" (Devarim 14:5). Radak - the Aleph and Vov are reversed. We find like this - Keves and Kesev.
Radak: It is like a Toa (wild ox) lies in the net in which they trapped it. Michmar is a net - "Yiplu v'Machmorav Resha'im" (Tehilim 141:10).
Malbim: It cannot move from its place.
Why does it say "Chamas Hashem" and "Ga'aras Elokayich"?
Malbim: "Chamas Hashem" corresponds to the cup of anger, and "Ga'aras Elokayich" corresponds to the cup of Tar'elah.