Well, dunno if I would agree with the too large sail (sail means the tower/bridge?). It is not bigger than on my last submarine designs, but it may lokk a little bit massive due to the enclosed AA tower. Which answers your second question. It is supposed to be a 2 cm twin AA gun with 90 degress elevation. I know it is not an optimal place for a AA gun.... the secodn gun is a 90 mm deck gun.