What is the meaning of "u'Mah Ya'aneh Mal'achei Goy"?
Rashi: What will they tell in the days of Chizkiyah, messengers of Yisrael who go to give tidings?
Radak: Every messenger of Goyim, who goes on a mission from land to land, when they ask him the news, what will he say?
Malbim: When Peleshes send messengers to ask about where the fire and smoke are going [what will they answer]?
How did Hashem found Tziyon?
Rashi: He established a proper king, and strengthened His nation. Radak - Chizkiyah was like a foundation for a building. Melech Ashur thought to destroy it; Chizkiyah prayed, and Hashem answered him via Yeshayah ha'Navi "v'Lo Yoreh Sham Chetz v'Lo Yekadmenah Magen v'Lo Yishpoch Aleha Solelah; v'Ganosi Al ha'Ir ha'Zos Lehoshi'ah" (37:33, 35).
What is the meaning of "u'Vah Yechesu Aniyei Amo"?
Rashi: Even from the 10 tribes will come there, like it says in Divrei ha'Yamim (II, 30:6) that Chizkiyah sent messengers in all borders of Yisrael to repent to Hashem.
Radak: All fortified cities of Yehudah were captured and [Yerushalayim] alone remained, and Yisrael took refuge in it.
Malbim: Hashem felled Melech Ashur in front of Yisrael. Even though Pelishtim rejoiced over the fall of Yehudah, the salvation of Tziyon turned to be a good tiding for them, for via it they were saved from a greater enemy - Sancheriv, who totally destroyed them.