1)
Why does it say "El Pelishtim"?
1.
Rashi: This is like Al Pelishtim. Radak - also "El he'Harim Lo Achal" (Yechezkel 18:6) is like Al he'Harim, and similar verses.
2)
When did Pharaoh strike Azah?
1.
Rashi citing Seder Olam 26: When Nebuchadnetzar besieged Yerushalayim, in Tzidkiyah's 10th year, Pharaoh's army left Egypt, and the Bavliyim departed from Yerushalayim. Pharaoh heard, inundated Azah and returned to his land. Radak - at this time Yirmeyah prophesized that Bavel's army will strike Eretz Pelishtim.
