1)
What is the breached wall?
1.
Malbim: It is the north wall of Yerushalayim. Yo'ash breached it from Sha'ar Efrayim until Sha'ar ha'Pinah.
2)
Why does it say "va'Yischazak va'Yiven"?
1.
Malbim: There he built a double wall with towers in it ? "va'Ya'al Al ha'Migdalos vela'Chutzah ha'Chomah ha'Acheres." It is called "ha'Chomah ha'Rechavah" (Nechemyah 3:8).
3)
What is "Shelach"?
1.
Rashi: They are weapons, like "Ish Shilcho b'Yado" (23:10).
2.
Radak: It is a sword; it is [also] a general term for all weapons.
3.
Malbim: It is a sword with a pointed end that can stab like a spear.
