Why should they be Metamei the Bayis?
Radak: Do not be concerned if you kill in the Beis ha'Mikdash and Metamei it via the dead bodies, for they were Metamei it first with their idols.
Malbim according to the metaphor: The rebellion will begin around the Mikdash. The killing will spread among them to Chatzros ha'Mikdash, and from there to the city, and a man will kill his brother.
What is the tense of "u'Mal'u"?
Radak: It is a command, which should have a Dagesh [in the Lamed], but it is omitted. We find like this - "u'Vakshu vi'Rchovoseha" (Yirmeyah 5:1), "Ki Lo Mal'u Acharai" (Bamidbar 32:12), "va'Ykan'u Vo" (Bereishis 37:11) and similar verses.
Which Chatzeros are discussed?
Radak: The Chatzeros of the Mikdash - Ezras Anashim, Ezras Nashim and Har ha'Bayis.
