1)
What is "Matzav Pelishtim"?
1.
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.
2.
Radak citing Targum Yonasan: It is army officers. Bereishis Rabah (3:6) supports this.
2)
To where did the Matzav go?