1. Gas miner
I'm also missing the ability to do anything with planetoids, like transforming them in some sort of mining station. Or (small) planet cracker technology?
2. Planetary Bombardment
Agree, I would love to have special ships designed for proper bombardment, instead of this brute force attack. Or even special ground forces that focus on sabotage, weakening militia defenses (is weird that all population helps in the fight. Big amount of civilians should actually become a hindrance for the military forces defending the planet
The theme for the next DLC is already pretty set: it's the Gardeners (and aquatic bio-engineering faction) and a terraforming revamp. We just need to formalize the plans for actually getting it done.
4. There should be a new limited, tech for adding a System slot
Agree, ship design gives many potential options, but in practice is rather limited to type of weapons, best armor/shield available (unless you want glasscannons), minimum needed generator, and expectionally you might want to add extra munitions.
5. Stop Anti-Missiles and Point-Defenses from being able to strike planets and large orbitals.
Although it makes sense that short range weapons shouldn't be able to hit planets, it wouldn't really make any difference save very extreme situations.
6. Do beam vs kinetic weapons need a rethink?
Or rather, the effectiveness of shields
7. Contact Station
Reminds me of diplomatic stations from GalCiv2. Basically they generate cultural influence on nearby planets/systems (population from the planet affected likes your faction and might want to defect) and diplomacy booster. There was also merchant stations that boosted the income from trade, but this feature is probably too simplistic on SiS to work on it.