1)
Why does it say "b'Af"?
1.
Ibn Ezra: Chase them with Your anger, so You will catch them 1 and destroy them.
2.
Palgei Mayim: Chase them with anger, in order that they will be destroyed.
1
Obviously, Hashem can catch them even if He pursues without anger! Perhaps without anger, He might decide that being chased was sufficient punishment, and He need not catch them. (PF)
2)
Why does it say "Shmei Hashem"? He addresses Hashem?
1.
Ibn Ezra: Indeed, it means Shamecha. This is like "v'El Moshe Amar Aleh El Hashem" (Shemos 24:1).
