1)
Why is it called "Beis Kodshenu v'Sif'artenu"?
1.
Malbim: There, our fathers learned fear and love of Hashem - "Lema'an Tilmad Leyir'ah Es Hashem Elokecha" (Devarim 14:23).
2)
Why does it say "Haysah li'Srefas Esh"?
1.
Radak: Bayis Rishon and Sheni were burned and never rebuilt in the Nochrim's hands.
3)
What is "Kol Machamadenu"?
1.
Radak: The Beis ha'Mikdash.
2.
Malbim: It is Torah and Mitzvos. All depended on Kodesh, Mikdash and Kadosh places. If You will return them to us, we will be Your nation like before, and prepared to receive Divine influence.