1)
Why does it say "Elokei Yisrael"?
1.
Radak: Hashem took vengeance for Yisrael from them.
2.
Malbim: The destruction of Mo'av is because they harmed Yisrael.
2)
What is "Kiryasayim"?
1.
Radak: It is the name of a city. Perhaps its name is 'double' because there were two towers in it.
3)
What is "ha'Misgav"?
1.
Rashi: It is a place (Radak - city).
2.
Radak citing Targum Yonasan: It is the house (place) in which they put their hope.