What mountain is this?
Radak: It is the rock.
What is the meaning of "Nechpaz Laleches"?
Radak: He was anxious and rushing to flee Sha'ul, but he could not, for Sha'ul and his men surrounded him. Even though it says that Sha'ul was on one side, when he saw that David wants to flee, they surrounded the rock. He needed only to seize him, when the messenger came (verse 27) and said that Pelishtim overtook the land, through Hashem's Hashgachah.
Radak (from Shochar Tov 18): About this, David said "Ani Amarti v'Chafzi Kol ha'Adam Kozev" (Tehilim 116:11) - even Shmuel is false! I.e. Sha'ul was about to trap him; in vain Shmuel anointed him and said that he will be king. Where is that promise?! Hashem told David, I will testify about him - "all Yisrael knew
What is the meaning of "Otrim"?
Rashi (from Shochar Tov 18): They surrounded and went around from one side to another, like an Atarah (crown) that goes around the head. Radak - this is like "ka'Tzinah Ratzon Taterenu" (Tehilim 5:13).