1)
What is the meaning of "v'Halchu Arei Yehudah"?
1.
Rashi: They went from Arei Yehudah.
2.
Radak (10): It means the residents of Arei Yehudah. The same applies to "v'Chol ha'Aretz Ba'u Mitzraimah" (Bereishis 41:57).
3.
Malbim: Every city went to scream to its 1 idolatry.
1
Verse 13 says that each had its own idolatry. (PF)
2)
Why does it say "v'Yoshvei Yerushalayim"?
1.
Malbim: Each neighborhood in Yerushalayim went to scream to its special idolatry.