Why does it say "El Derech"?
Radak: This is like Al Derech. The same applies to "El he'Harim Lo Achal" (Yechezkel 18:6).
Malbim: Aro'er is at the corner of the Midbar, separated from the settled area. Stand to the side of the road, and not to the side of the Midbar.
What is the meaning of "Sha'ali Nas v'Nimletah"?
Rashi: Ask one of these fleeing and escaping from Mo'av.
Radak: Residents of Aro'er should stand on the road and ask those fleeing from other cities of Mo'av, to which the enemy came first
Why does it say "Nas" (masculine) and "v'Nimletah" (feminine)?
Radak, Malbim: Ask, whether the fleer is a man or woman.
What is the meaning of "Mah Nihyasah"?
Rashi: Did anything escape destruction?
Radak: What evil was among them?