1)
What surrounds the city?
1.
Rashi: Chamas and quarrels. Radak - the city is full of these; it is as if it is surrounded by them. All their counsel is evil for me "Yomam va'Laylah."
2.
Malbim: It is as if Chamas and quarrels guard the walls of the city.
2)
What is "Amal va'Aven b'Kirbah"?
1.
Radak: Those who dwell in it think evil about me.
2.
Malbim: It is as if Chamas and quarrels rule in the city.