Pretty close. Main-gun magazines were indeed under the turrets. In a big ship the secondary magazines might be centrally located for equal distribution to all guns. Boilers are under the funnels; engine rooms usually further aft. Fuel tanks were spread around the ship for balance and to keep from losing all fuel with one strike.
As for 'weak-spot' drawings in the ID book, the real guys never had it so good. As has been pointed out before, sometimes the picture and description they had wasn't even for the right ship.
