What is the meaning of the first half of the Pasuk?
Rashi: Water will flow from their springs - A king will arise from their ranks who will rule over many nations. 1
Targum Yonasan: Their kings and their redeemers will come from their own ranks, and their children, the sons of Ya'akov will rule over many nations.
Rashi: He will succeed
To whom does "Malko" refer?
Rashi, Ramban, Rashbam and Targum Yonasan: It refers to Shaul ha'Melech
How could Bil'am name the king of Amalek before he was borm?
Ramban #1 (citing Rashi): Bil'am is pre-naming Agag before he was born. 1
Ramban #2 and Rashbam: All kings of Amalek were called Agag. 2
And what is the meaning of "Vesinasei Malchuso"?
Rashi and Ramban,: It means that they will go from strength to strength, because David and Shlomoh will follow.
Targum Yonasan: And because he (Shaul) had compassion on him (Agag), his kingdom was taken away from him.