Some observations

[Suicide Junkie]

The key thing will be that top speed does not depend on your engines. The built-in top speed of the hull would be very high, the built-in turn rate and built-in acceleration would be zero.

Engines would add to the turn & accel. Engine damage would thus force you to go in a straight line, and prevent you from slowing down (top speed is always above current speed)

You could only set desired speeds in increments of 25% (of lightspeed, perhaps) with the keyboard, but with mouse controls, you can get it in 1-pixel increments.
If the acceleration is low enough, you don't need to worry - just press full throttle to accelerate and zero to slow down. When at your desired speed, you can click the mouse where the speed line is to set cruise control, or just alternate between gas and brakes.