Who are "Zarim"?
Radak: They are foreigners.
What is the meaning of "Zeruha"?
Rashi: They will scatter [the residents]. Radak - this is like "Mezare Yisrael" (31:9). The verse uses a word similar to the previous word (Zarim) for a fluent, flowing expression.
Radak: Perhaps it is the same root as Zarim 1 . Zarim is a To'ar (kind of person), like Dovim, Kelim. Yonason translates like this - plunderers will plunder it.
Malbim: They will surround it like a Zer (rim), and empty the land.
Radak: In Zarim, the middle letter of the root is omitted. In Zeruha, the last letter of the root (Hei) is silent. Normally, there should be a Dagesh in place of it, but Reish does not accept a Dagesh.
What is the meaning of "vi'Yvokeku"?
Rashi: They emptied it. Radak - this is like "Vekakum Bokekim" (Nachum 2:3).
Why does it say "Ki Hayu Aleha mi'Saviv"?
Malbim: Had they wanted to leave a remnant, they would have surrounded it from only three sides, like the Rambam writes (Hilchos Melachim 6:7), so they can flee from the fourth direction. They surrounded from four sides [so there would be no remnant].