The weapons actually are on turrets, this is most evident when the attacking ship is moving, and fires at ships it isn't directly pointing at. You will also notice that when a capital ship attacks a vessel, it points it's most powerful weapon at it, some of it's weapons can not hit the primary target, so will attack something else instead. This is the easiest to see with the ships that broadside their enemies (the Carrier and the two Battlecruisers) You can often see weapon fire from their ends hit other ships.
Now as for what you are talking about, ships trying to avoid and outmaneuver each other, I don't know if things like that are planned. I really hope that they do though, I'm a Homeworld man and I like the movement in those battles.
I think that there is hope for this because of a couple things I have heard and noticed. The first is that someone (can't remember who, sorry) said that he modded a capital ship. He removed it's front weapons (which used to be it's primary ones) and added much more firepower to the sides. This ship realized that he had done so, and the new ships now broadsided the enemy instead of just facing them. This means that ships aren't hardcoded as to how they should face enemies, they figure it out themselves. The remaining piece of the puzzle is for them to recognize the enemies strongzones and avoid those. In one of my battles in the early game a system was attacked by like a dozen frigates. I sent my carrier there to fight them. While they were distracted I built a gauss cannon behind them. So there was the gauss cannon, the frigates near the end of it's range, and then the carrier. The second the cannon was finished all of the frigates gunned it and left it's firing range. Now, I have only seen behaviour like this one time in the several games, so I'm not sure I actually saw what I thought I saw. Certainly my own ships have sprinted past gauss cannons often enough. But it is possible that ships have it as a minor priority to leave the range of stationary enemies, something which they will try to accomplish when it doesn't slow them down too much. I am skeptical though, but I'll look for that behaviour more often now.