Rashi: Armies make Matzav and Mashchis. The latter is a garrison that runs after spoils of the city. The Matzav are Netzivim to guard lest people leave the city to despoil them.

Radak citing Targum Yonasan: It is army officers. Bereishis Rabah (3:6) supports this.

Rashi: Michmash is a mountain. It is opposite the mountain Geva, where Yisrael ¹ were. There was a canyon in between. They went to the side of Michmash closer to Geva.