1.) No effect. The inbuilt tracking system fires at 1,000 kilometers with 4x your empires maximum tracking speed tech.
2.) Higher tech turret gear reduces the space required to bring the weapon up to 4x tracking speed. Note that it takes more gear when your empires tracking speed itself increases.
3.) ECM is actually given multiplied by 10; i.e. an ECM 1 gives a ship an ECM score of 10. Therefore, a half strength ECCM gives an ECCM score of 5 per tech level.
4.) It's irrelevant for CIWS, which will always be turreted.
AFAIK the turret tracking speed is always used if a weapon is mounted in a turret.
Otherwise, the game always uses the higher of the ship's speed or the empire's basic tracking speed tech. This sets the WEAPON's tracking speed level. However, what determines the final tracking speed used is still determined by the Beam Fire Control; in other words, the shot will use the lowest tracking speed of either the Fire Control or the Weapon when taking any given shot.
An unturreted laser mounting on an immobile satellite has a tracking speed of 4,000 kms because of it's empire technology. A fire control with 16,000 kms tracking speed is used to target an enemy ship. The shot is only fired at 4,000 kms because the weapon cannot track faster than that even though the fire control can. The same applies in the opposite situation of a high-tracking speed weapon and a low-tracking speed fire control.