What is the meaning of "va'Yasimu ha'Am"?
Rashi: He prepared them near the wall to fight, like it says about Ben Hadad (1:20:12) "va'Yasimu Al ha'Ir."
Radak: The ambush and the camp drew closer to the city than they were.
Malbim: He put the 5,000 men west of the others on the north.
What is "Akevo"?
Rashi (27:36): This is like the Targum (he outwitted me). Radak
Why does it say that he spent the night in the Emek (valley)?
Rashi (from Megilah 3a): He spent the night in the depth of Halachah.
Radak: He went with others in the valley in which the camp was, to see whether the guards are awake or asleep, lest the people of Ai come upon them suddenly and strike them.
Malbim: There was a valley between the camp and the city. At night, Yehoshua and his men went into the valley, to approach the city.