If you back the terraformers will Synedrion ever get the mist repeller technology?
Also, if you are between 50% and 75%, do you get any additional technologies that they research later in the game? Are there any additional perks that you get at 75% that you don’t get at 50% (besides unlocking certain faction missions)?
Mist repellers can be built after the research “Mist Repeller Development” (cost: 3000).
This research depends on “Advanced Nanotechnology” (cost: 700) …
… which depends on “Sentient AIs” (cost: 200)
There is no dependency to story related content.
Of course, allying with Synedrion is the quickest way to have them.
The answers to the OP three questions are yes, yes, and yes with the third yes being access to their known but as yet unresearched tech items and ability to research them directly.
I’d like to know besides the mission to plant seeds what does backing the terraformers even accomplish? I haven’t noticed any concrete effect to come from it. No new tech as far as I know, no noticable impact on the world, not even a follow up on the seeds.