1)
What do we learn from "v'Gam Yehudah"?
1.
Rashi: Also Yehudah will fight against Yerushalayim, amidst coercion.
2.
Radak: Also Yehudah, who will be forced to fight against Yerushalayim, when they see the frenzy that Hashem will put on the Goyim, they will gather the Goyim's wealth - "v'Achlu Al Yamin v'Al Smol" (12:6). Afterwards Yoshevei Yerushalayim will go out and plunder, too.
3.
Malbim: Also Bnei Yehudah who remained in Yerushalayim - "v'Yeser ha'Am Lo Yikares Min ha'Ir" (2), when they see that Hashem confounded the Goyim, Bnei Yehudah will go out to fight. Via this, they will gather their wealth.
2)
What do we learn from "v'Usaf Cheil Kol ha'Goyim"?
1.
Refer to 14:14:1:2-3.
