What is the meaning of "Yizkor"?
Radak: He will smell (accept their Korbanos), like "Azkarasah la'Shem" (Vayikra 6:8).
Malbim: Even though now he cannot offer Korbanos like normal, before the war starts, Hashem should remember all the Menachos and Olos that you offered until now.
What are "Minchosecha v'Olasecha"?
Rashi: They are Tefilos that you pray in war.
Radak: When David went to war, they offered Korbanos for him, that Hashem should save him. They offered on a Bamas Yachid, or on the Bamah Gedolah in Giv'on.
What is the meaning of "Yedashenah"?
Rashi: It is an expression of obesity. I.e. He should accept them with desire, like fat Olos.
Radak: He should make it ashes. I.e. He should send fire to burn it, and accept it with desire.
Malbim: Hashem should remember the ashes of the Korbanos that you offered until now.
Why does it say "Selah"?
Malbim: This concludes the first part of the Mizmor (what they prayed for David in Tziyon).
