1)
For what did He choose David?
1.
Radak: There will be no king in Yerushalayim, other than David and his seed after him.
2.
Malbim: To be the shepherd over the flock (Yisrael).
2)
What are "[mi']Michle'os Tzon"?
1.
Rashi: They are pens for flocks, like "Gazar mi'Michlah Tzon" (Chabakuk 3:17).
2.
Malbim (citing a Midrash): Hashem chose David due to his conduct of the flock (refer to 78:71:1:1).
