Why does it mention that one of Sha'ul's servants was there?
Malbim: Achimelech was not careful not to help David in front of him, for he had no idea that David was fleeing Sha'ul. Do'eg heard David say that he is doing a Shelichus for Sha'ul, and even so Do'eg falsely slandered Achimelech.
What is the meaning of "Ne'etzar Lifnei Hashem"?
Rashi: He stopped himself in front of the Ohel Mo'ed to engage in Torah.
Radak: He came with others to sacrifice; his friends left, and he stayed to pray or sacrifice more.
What is "Abir ha'Ro'im"?
Rashi (from Shochar Tov 3): It is the Av Beis Din.
Radak: He was the greatest of Sha'ul's shepherds, and appointed over them.
Why was he called "ha'Edomi"?
Radak: He was from Eretz Edom. Also Uriyah ha'Chiti, Yeser ha'Yishmaeli and Iti ha'Giti were called by the name of the place they lived.
