1)
Why did David tear his clothes?
1.
Radak and Malbim, both citing Mo'ed Katan 26a: We learn from here that one tears for [hearing of the death of] the Nasi or Av Beis Din. Sha'ul was the Nasi, and Yehonason was the Av Beis Din. We learn that one must tear for both, for [verse 12] mentions each. 1
1
The verse is only an Asmachta; Nevi'im and Kesuvim cannot directly teach Halachos. (PF)
2)
It is written bi'Vgado, and we pronounce it bi'Vgadav!
1.
Radak: The writing teaches that one must tear only [one,], the outermost garment. The pronunciation teaches that David tore for Sha'ul, and for Yehonason, and for Am Hashem.
