1)
Why did he appoint 12 Netzivim, one for each month?
1.
Malbim: This was to lighten the burden [of supplying the needs of the king's house, which was great] on Yisrael. He divided Eretz Yisrael into 12 regions, and each needed to supply his needs for only one month a year, and the rest of the year they had respite.
2)
How did they finance the king?
1.
Rashi: They gave to him meals, food for his horses, and all his expenses.
