1)
Why did we praise Hashem the entire day?
1.
Radak: In front of the enemies, we praise ourselves in You, and say that we have Elokim who will save us from them. All days [he is gracious and lends]. Kol ha'Yom is all days; the same applies to "Osecha Kivisi Kol ha'Yom" (25:5).
2.
Malbim: It is to aggrandize Your name. We have no strength or counsel for war! Refer to 44:8:1:2.
2)
Why does it say "l'Olam"?
1.
Radak: [Your praise] will not cease from our mouths the entire length of the Galus.
3)
Why does it say "Selah"?
1.
Malbim: This completes the matter.
