What is the meaning of "Yiplu v'Michmorav Resha'im"?
Rashi: The Rasha himself will fall in the net that he set for my legs. Radak - it says Michmorav (singular), i.e. of Sha'ul; Resha'im is plural, to include those who consented with him to pursue David.
Malbim: I do not require that they die, just they should fall in it; there, all of them will be stopped together, until I pass. Then, they will leave without mishap. I do not desire their evil, only that they cannot harm me. And so it happened; they were detained via the war with Pelishtim until David and his men were saved.
What is the meaning of "Yachad Anochi Ad E'evor"?
Radak #1: The words must be re-arranged; Ad E'evor Anochi. I.e. I will pass and not be caught in their trap.
Radak #2: We need not re-arrange the words. "Ad" is like Adei Ad (forever) - "v'Al la'Ad Tizkor Avon" (Yeshayah 64:8). They will fall in their trap, and I will always pass, with security that I will not stumble in them or in others.