the ship isn't finished (that's why the fences and so on aren't there.) for the gun, I refer to primer's post: this is really an multirole gun for this ship, because it needs to do land attack (sometimes, not an main role), antiship and anti-air.
also, all ship guns are artillery
they all fire grenades in an curved track, so they are artillery....... I think you meant land attack with it.
and thanks for the compliment that I have improved, now you can see how much you can learn on sb in 4 months