I am wondering what is the best speed in-combat for turn rates? I seem to think it's half impulse but is there a better speed at which to operate in-combat when considering turning speed?
Turn rate is actually independent of your speed. (Well you do need a certain minimum speed to archive your normal turn rate. The thing that your ship speed affects is the turning radius. The faster your speed the bigger the turning radius. That means the faster your go the further your have to travel in order to make the turn.
The best turning rate is actually the minimum speed one much be at to archive your normal turning rate. But the minimum speed might be too slow for tactical movement. For example, you might want to keep in the arc of a downed shield facing as an enemy ship is maneuvering. Sometimes, I'll drop down to 1/4 throttle on a Science or Escort and turn in place in order to pound on a Battleship which has a downed shield.
1/4 impluse is the lowest speed for optimal turn rate. As for your ship's controls, the best advice I can give you is play the game, play with your throttle controls, and get a feel for you ship's turn speed, turn radius, and speed controls.