1)
Why did he rise?
1.
Malbim: It was to bless [Baruch Dayan ha'Emes over his children's death] while standing.
2)
What is the meaning of "va'Yagaz"?
1.
Rashi: He detached [hairs of his head]. The Targum of "Gazi Nizrech" is Telishah (detaching). Ibn Ezra - also "Horidu la'Aretz Roshan" means the hairs of their heads.
2.
Devar Eliyahu: He uprooted (cut) hairs in the middle. He did not uproot them from the roots - the Torah forbids Karachah 1 ! Malbim - we can say that he made Karachah over the loss of his animals. The Torah forbids Karachah only amidst grief over a person who died.
