Why did Yehoshua command to go to their cities only after finding the kings?
Malbim: Initially, he planned to rest first in Gilgal. Now that through Hashgachah, their kings fell, he decided to attack the cities before they appoint new kings.
What is the meaning of "v'Zinavtem"?
Radak: Cut off their tails, i.e. the end of their camp.
Malbim: Cut off also the tail of the camp, i.e. the remnant.