1)
Why will you call a nation that you do not know?
1.
Rashi: You will call them to serve you, if you will heed Me, for the sake of Hashem called on you.
2.
Radak: You do not know them, for they are far from Eretz Yisrael. They will come in front of you, even though they did not know you until today, when they hear the wonders that Hashem did for you. They will fear you, and run to do what you command them.
3.
Malbim: You will call them "Lema'an Hashem Elokecha" - to [the true] Emunah.
2)
Why does it say "Elecha Yarutzu"?
1.
Malbim: They themselves will run to do your will [even without a command].
3)
Why does it say "Ki Fe'arach"?
1.
Radak: Who gave this glory to you? "Hashem Elokecha"!
