Hope you don't mind if I add my two cents in!

For railguns I'd like to add more differentiation to them rather than just being high projectile velocity but slow tracking.

If it were up to me, I'd make them fixed (not turreted), and only mountable on heavy ships. On one hand I think it would be neat to restrict them to spine only mounts, but that would require having to redo the entire weapon system so I think we can safely rule that one out.

Another aspect that might be interesting is having them greatly increase the heat of the ship firing them due to the relatively greater amount of heat generated versus convention projectiles.

And lastly, to balance out their high projectile velocity, I'd steal borrow from Elite:Dangerous, and introduce some sort of charge up/spool up time that can be attributed to having to charge up the railgun's capacitors.

For asteroids, depending on how far they want to go in keeping meteorites in-game as a feature, I'd suggest adding anti-meteorite variants to the existing projectile weapons. Unlike ships, meteorites aren't going to perform evasive maneuvers or use electronic countermeasures. I'd use that as the basis/reasoning for having a meteorite specific variant.

These variants would have significantly superior tracking, accuracy and importantly: range versus meteroites, while being significantly inferior versus spaceships.

For armor, I'm from the school of thought of making (theoretical) spaceships as light as possible. Better to not get hit than get hit at all. I'm curious how much extra protection thicker armor would give before it makes a spaceship impractical to move around? (Assuming you're not going to go all the way and build an immobile fortress).

I'm reminded how during WW2 tank designs were built around thicker and heavier armor, only for them to get lighter and thinner post-war as the anti-tank weapons increased in penetration power to the point of making lumbering armor obsolete.

As a compromise, maybe military ships could have the option of spaced armor and composite armor (alá Chobham armor) as expensive, high-tech tree options. I'd also imagine that any corporation capable of producing such armor would be extremely hesitant to sell it to other corps.

Thinking out loud and brainstorming ideas like these is real fun :>

Hmm, that give me an idea for another upgrade for armor slot - "Armor reduction" that gives boost to agility/acceleration

After some more combat, I'd love to see rapid fire (2 or 3 time bigger fire rate) version of current basic turret as an alternative to flak.