Many turrets have a "locked" low drag position for cruise and an "open" active position for actually using them. I think the default key combination to toggle this is ctrl+O.
As for the actual control, many turrets also have two controls. The mouse moves the gun within the confines of its mounting mechanism. However, some turrets also have movable mounting brackets too in order to alter their field of fire. I have mapped those to the arrow keys.
Take note however that moving the mounts themselves is not instantaneous, as it simulates the need to unlock the mount before moving it and lock it back into place at the desired position.
Also, check the frequently asked questions thread conveniently stickied on the front page for the most common questions:
http://forum.1cpublishing.eu/showthread.php?t=24782