1)
Why is it called Giv'at ha'Aralos"?
1.
Rashi: It was called so do to this event. The cut foreskins made a mound.
2)
Why does it say "El Giv'at ha'Aralos"?
1.
Radak: It is as if it says b'Giv'at ha'Aralos. We find like this "Nafal El ha'Mayim" (Melachim 2 6:5).
