What is the meaning of "Noda David"?
Rashi: He contemplated how to guard himself from Sha'ul.
Radak: He became known. It was known that there were men with him, and Sha'ul heard. When Sha'ul heard this, he thought that David rebels against him and plans to ambush and fight me, or to divide my kingship. He said (verses 8, 7) "Hekim Beni Es Avdi l'Orev", "l'Chulchem Yasim Sarei Alafim" (he will make you officers) in the army he gathers against me, or when he will be king!
Malbim: Before he heard that men gathered to David. Only now he learned their location.
What is "ha'Eshel"?
Radak: It is a tree, like "va'Yita Eshel" (Bereishis 21:33).
Where is Ramah?
Rashi: It is in the border of Binyamin.
Rashi citing Ta'anis 5b: This is the Ramah of Shmuel; it is different [than Ramah of Binyamin]. The Midrash is, Sha'ul sat in Giv'ah in the merit of the great Eshel (Shmuel) in Ramah, who prayed for him.
If he was in Giv'ah (a valley), he was not in Ramah (a high place)!
Refer to 22:6:3:2.
Radak: It was a high place in Giv'as Sha'ul.
Malbim: The Eshel was between Giv'ah and Ramah; it marked the border of Ramah.