1)
What are "Zivchei Seru'ah"?
1.
Rashi: They are Korbanos over which I say Shirah.
2.
Radak: They are Korbanos with praise and thanks that He saved me from many enemies.
3.
Malbim: One who fights and defeats his enemies offers Korbanos of Teru'ah, i.e. Korbanos Todah for the Shofar blasts of war and the victory - "v'Chi Savo'u Milchamah... va'Hare'osem ba'Chatzotzeros" (Bamidbar 10:9). However, I will be in Hashem's tent. Being there is the Teru'ah of war and the victory!
2)
For what will he sing?
1.
Radak: For all the Chesed that Hashem does with him.
2.
Malbim: For making my enemies fall in front of me [so I can sit in Beis Hashem].
