So some of the best research would have to be unlocked by successfully "interrogating" enemy captured faction leaders.
Heck, just do the exact same thing here. Give us a reason to go after them. I mean, after 30 planets, it's not like money or more slaves is an issue. Super-tech unlocks from defeating the leaders could be a fresh new sparkly to dangle in front of our faces.
So thinking more about ship combat overhaul. This doesn't need to be too complicated - I'm thinking Crusader Kings 2 number crunching is fine. No special effects required. Give visible ship stats like so:
1 - Class
2 - Hitpoints
3 - Damage vs Class
Example:
Class: Fighter
Hitpoints: 10
Dmg vs Fighter = 5
Dmg vs Bomber = 20
Dmg vs Capital = 1
Dmg vs Planet = 1
Class: Bomber
Hitpoints: 20
Dmg vs Fighter = 0
Dmg vs Bomber = 10
Dmg vs Capital = 30
Dmg vs Planet = 10
Class: Screening Frigate
Hitpoints: 100
Dmg vs Fighter = 10
Dmg vs Bomber = 10
Dmg vs Capital = 5
Dmg vs Planet = 5
Class: Planetary Assault Cruiser
Hitpoint: 250
Dmg vs Fighter = 1
Dmg vs Bomber = 2
Dmg vs Capital = 10
Dmg vs Planet = 100
Very simple and gives more of a "right tool for the job" approach to engaging enemy fleets & planets.
Now as far as tech research goes, oh the possibilities are endless, but right off the bat I can see a need to start with dividing them all into two types: New Stuff and Improvements. New stuff would be the unlocks that give new ships, furniture, cybernetics, slave procedures, etc. Improvements would be all the mods and stat upgrade stuff that is done with things you already know (or have unlocked).
So you put points into the red branch and unlock "slave hormone treatment," which give +/- 1 point per month of body change. This would also unlock "improve slave hormones" on the blue side. This would a
repeatable option that increases that change value every time that it is repeated. So research it once and you now do +/- 2 points per month. Again an you have +/- 3 points and so on.
One last request: Could the chronosphere thing that controls aging also be made to effect pregnancy as well? Speed up, slow down or even freezing it in place until we're ready to deal with it? That would be awesome!