1)
Why does it say "Ki Lo b'Kashti Evtach"?
1.
Radak: We do not go to war confident in our strength, rather, in our G-d and our [Divine] help.
2.
Malbim: It is impossible that You will leave us to chance and nature, that we ourselves will fight the enemy. This is improper from the aspect of the actor, and of the action. From the aspect of the actor - I do not trust in my bow. We are not trained to fight with bows. From the aspect of the action - my sword will not save me. The sword opposes us; Yakov was not given a Bris of the sword (it says about Esav "Al Charbecha Tichyeh" - Bereishis 27:40).
