When is "Es Ketz"?
Rashi: When our redemption will come near.
Who is Melech ha'Negev?
Ibn Ezra: It is Egypt. It does not matter what their creed is.
What is the meaning of "v'Yista'er Alav Melech ha'Tzafon"?
Rashi: Melech ha'Tzafon will fight Melech ha'Negev. Ibn Ezra – he will storm against him. Yista'er is like "b'Sufah uvi'S'arah." If we read v'Yishta'er with a Shin, it is like "Heshiro 1 v'Lo Yadati" (Hoshe'a 8:4).
Malbim: Melech ha'Negev fights [the one discussed until now, Malchus Yishmael], and Melech ha'Tzafon will come to save Malchus Yishmael. It was already explained that Gog and Magog will come from the north to conquer Yerushalayim, and Melech ha'Negev will fight him.
This is an expression of removal. There, Rashi, and Ibn Ezra citing Yefes, says that it is Hesiru with a Sin, (PF)
What do we learn from "u'Va va'Aratzos v'Shataf v'Avar"?
Malbim: Afterwards, Melech ha'Tzafon will come to lands of Eretz Yishmael, and inundate them with his troops.
