1)
Why did David and Avishai go at night?
1.
Malbim (6): [Sha'ul's men] will think that they are from [Sha'ul's] camp.
2)
Why does it say "El ha'Am"? Verse 6 said "El ha'Machaneh"!
1.
Malbim: By the time the arrived, everyone was sleeping. 'Machaneh' has guards around it.
3)
What is the meaning of "Me'uchah"?
1.
Rashi: It is inserted. Radak - this is close to "Ma'uch v'Chasus" (Vayikra 22:24).