well, as Sonlirain said, AA is a big advantage of IJN BB's. but the game is about playing with your own style. full supports is not a bad thing, however, yammy and SY AA has more than range, fire rate, and damage going for it. i average about 2-3 sailor increases every 3-4 shoot downs with my SY. and i get alot of multiple sailor increases at once.

i played my fuso till i got the yamato, although my crew was much higher than the ship. I would say that you can play the yamato N's if ya want because the gun angles of the yamato is something that is hard to get used to since from angle 45-39 you don't really notice much of a range drop. For a recommendation power level your AA gunners to 90ish if you can bare to then class them as DP you will get a good AA reload and decent spread.

Least ya asked before using the ship, also the yamato benefits from having 7 tier 4 scouts on deck, it's a very useful scout ship and will server you well with it's heavy hitting guns. Good luck with your yamato.