You heard correctly, Johnny Cyclops. You need to raise the nose slightly to ensure maximum firing effectiveness. You'll notice it when one gun fires but the other refuses, because the firing solution involves firing through your own hull.
The primary advantage with gimballed weapons, in my experience, is that you can target subsystems with them. This is really useful for the big ships. Elite Anacondas (the ones you have to kill in the assassination missions) pack a hell of a wallop, so taking out their thrusters (confusingly labeled "drive" in the targeting menu) is a priority - they won't be able to jump out if you disable the thrusters, and they lose all control over attitude and momentum, which renders their weapons platforms largely ineffective.
It's much harder to consistently hit the systems with fixed weapons.
Hence I always recommend fixed lasers with gimballed multicannons. The cannons do much more damage per shot, but missing with them is expensive, and gimballed weapons miss quite often, especially when they're leading the target at range.
Another point to raise it that switching flight assist off increases maximum speed and reduces the turning circle - you can drag your ship's ass around so you're effectively flying backwards while thrusting forwards. Toggling it on and off gives you much better maneuverability without sacrificing too much stability.
On that final point, I do toggle FA off/on briefly if I get caught in a 'spiral' with a nippier NPC at close quarters. But with keyboard only, and rudimentary speed control, I've not got anywhere near mastering FA off all the time. And good to know my understanding of other weapons are right. Now I'm back from a exploration trip out to the Coalsack I'm ready for some combat/missions.