1)
What is the meaning of "va'Titosh ha'Milchamah"?
1.
Rashi: The war spread. 1 This is like "Netushim Al Pnei Kol ha'Aretz" (30:16), "va'Yinatshu ba'Lechi" (Shoftim 15:9) (and "va'Yitosh Al ha'Machaneh" (Bamidbar 11:31) - Radak).
2.
Radak citing Targum Yonasan: Those who make war (the soldiers) spread out.
1
Malbim: It spread to the battlefield, which is between the opposing Machanos.