1)
What is "Chatzer ha'Gedolah"?
1.
Ralbag, Abarvenel: It is outside Beis [Metzudas David - all Batei] ha'Melech.
2.
Gra: It is the entire Ezras Nashim.
3.
Malbim: It is around all the buildings.
2)
Where were the rows of rocks and cedar wood?
1.
Rashi: The wall consisted of three layers of rocks, and a layer of cedar wood on top of them.
3)
What does it teach about Beis Hashem?
1.
Radak: The inner Chatzer of Beis Hashem (6:36, i.e. the Azarah) and the Ulam were built like this.