1)
Why does it say "va'Yasger"?
1.
Radak: Many Yisraelim died in that war. Malbim - 30,000 died via the sword.
2)
Why does it say "uv'Nachalaso His'abar"
1.
Malbim: Due to Evrah, Shilo was destroyed, like it says above (verse 59-60).