1)
Who cast the lotteries?
1.
Malbim: The 24 men mentioned - the heads of the Mishmaros.
2)
What do we learn from "ka'Katan ka'Gadol"?
1.
Radak: This is like I explained above 1 (25:8).
1
I.e. they did not say that the older will be first and the younger second. Rather, they cast a lottery. There, there was a Havah Amina that the older will have precedence. Likewise here, one might have thought that the Gadol should serve at the most esteemed gate. (PF)
3)
What do we learn from "l'Sha'ar va'Sha'ar"?
1.
'Rashi', Radak: The lottery decides who will be on each gate - east, west, north and south, and all gates of the Azarah.
