1)
Why is Venayahu called Sar ha'Tzava?
1.
'Rashi': It is for his honor. The only other one called so was Yashav'am, who was also called Rosh, since he was from Bnei Peretz, like David.
2.
Radak: It is because he was the head of the 30 Giborim (6).
2)
What is the meaning of "ha'Kohen Rosh"?
1.
'Rashi': He was the head.
2.
'Rashi': Some say that he was Kohen Gadol; this is wrong. Tzadok and Evyasar were Kohanim Gedolim [in the days of David]! Radak - he was Kohen Gadol, like it says above (12:28) "Yehoyada ha'Nagid l'Aharon."
3.
Malbim: He was the head over the Kreisi u'Pleisi, like it says above (18:17).
