Since some of you are primarily interested in the capship AI section of the script I would like to know what you think about this in general.
What do you expect such a script to do? Not only "well it should make capships attack properly somehow" but more specific. For example: How do you think a smaller ship should attack a larger one (like cruiser/corvette attacks a destroyer) and what's different if the large ship is moving or not? How do you think the script should be controlled by a FREDer and with which options?
A couple of basics would be engagement range/behavior settings, with defaults set based on configs (configs should specify default range/behavior, a and an engagement vector (broadside=1,0,0, forward=0,0,1). So like, a button to attack from long/medium/short range (with user defined range values for each?), and a button toggling between direct assault, flanking, circlestrafe, etc maneuvers. A parameter to specify whether ships should strafe, maintaining orientation relative to target, or travel forwards would be good.
Additionally, setting aggressiveness (whether ships should actively pursue new targets/hold position/hold fire) would be a good control for all craft.
Another control would be setting PD turret behavior (prioritize strikecraft, prioritize bombs, augment main turrets (potentially targetting enemy subsystems?).
Finally, a control to select between missile loadouts (like in that one WiH Tenbara mission) would be good.
As far as FRED control, I think a main function with various parameters (AttackShip(ControlShip, TargetShip, Range, Behavior)) would be nice, as well as functions to change individual parameters (ChangeRange(ControlShip, Range)).
Ship grouping could be taken into account as well (whether ships should cluster together, spread apart, not care).
A general attack order could also have a ship focusing on taking down a specific chain of subsystems? (Main guns, then weapons engines, then engines?)
For carriers, a series of "strikecraft attack" buttons would be cool (ie, capital ship selected, use the fighter attack command on an enemy convoy, capital ship deploys fighters with attack orders on convoy. Of course, this would require carriers to keep track of the fighters it holds.
These are all rather high level functions, but I think they'd greatly enhance the RTS experience, and would probably make fredding easier as well.