1)
What is "Beis ha'Am"?
1.
Rashi: They are Batei Kenesiyos. Radak - this is a Klal; it is like Batei ha'Am.
2)
When did all this occur?
1.
Malbim: It was in the fifth month, like it says in Melachim II, 25:8 and below, 52:12.
