One hull type I'd like to see is "Invincible" so you don't have to pore through all the immunities and guess whether that means it's invincible.
Light bonuses (and similar) aren't that important because with enough raw power you can chew through the HP of most of those units without multipliers. Ultra Heavy is a different matter, you'll need a massive high-mark fleet (the kind that only the AI can afford) to bring one capital ship like that down and the AI has the advantage that the player's goal is the total annihilation of all mobile forces on a planet, not just hit and run on the command station so there's more time to kill those capital ships.
Seems pretty normal to me that capital ships require using heavy weapons but with fleetships it often gets confusing which of the half dozen types deployed by each side in a battle will eliminate which other type quickly and which ones will get to use their full health.
One thing I don't see people here talk about with armor is that armor punishes using multiple small shots over one big shot, that's the main point of armor (forcing enemies to deploy awkward heavy weapons and seeing all their cool mass killing guns invalidated, especially since weapons designed to penetrate armor can be rather crappy when it comes to damaging what's behind that armor compared to non-AP weapons). Armor disproportionately impacts ships with high rates of fire (unless they're crazy rapid fire doom cannons like the Cursed Golem). In fact I suspect the swarmers are currently the only units affected by armor at all (when you've got damage in the quadruple digits those 1.5k armor will suddenly matter), further skewing the game against them.
If we go by real life then armor is an all-or-nothing affair, damage to the armor by previous hits doesn't matter all that much because the holes are so small that you probably won't hit them twice. You penetrate or you don't. Company of Heroes uses that model, armor doesn't reduce damage, it determines the probability of a shot actually doing damage (I think shots that fail to penetrate still do something like 5% of their original damage). Higher AP means a shot has a higher chance to penetrate against armor of a certain strengths, a gun designed for hitting soft targets may pierce the armor on an armored car but will have next to no chance of ever denting the heavy armor found on medium and heavy tanks (medium tanks are units like Shermans or Panthers, heavy tanks are Pershings and Tigers). Since AP in real life means kinetic weapons and kinetics lose speed in the atmosphere they actually work roughly like the old shields in AIW 3.0. Of course that makes no sense in a space setting and we already have radar dampening to reduce enemy ranges.
Hm, how is armor calculated against continuous beam weapons, by the way?