What about methane or ammonia breathers, I'll assume that oxygen can be swapped out for those, as long as either of the other toxic gasses aren't present?
There´s any way to edit the NPR stats after they are created? or do i need to create them as player races and then transform them into NPR, is this even possible?
Oh, and how do i add construction brigades on SM Mode?
I'm pretty sure you can't change them after you've created them, though there's 'space master options' on the intelligence window I can't access due to my resolution which may it may not be related.
You create NPRs in one of two ways, either under the spacemaster option on the main menu there is 'add extra NPR' which adds a new system somewhere with an NPR set up on a suitable planet, you can't edit this but it'll be created in the same way as any NPRs generated during system exploration, so further along the game it'll be larger and higher tech.
OR, under the system information window(f9) you can setup a new empire on any habitable world, that means any world which meets the requirements steve just listed, use the 'create empire button' then you get a window allowing modification of their name, theme, economy, tech points, etc, you can also change their max atmosphere pressure, gravity deviation, oxygen pressure deviation and temperature deviation.
Most importantly there's an option to create them as an NPR.
If you want to add a new empire to an unsuitable planet you'll first need to terraform that planet, create a colony there using a pre existing empire and use spacemaster options to modify the planet. Oh and you should use teh 'homeworld minerals' button to make sure they don't run out and die early.
Finally adding construction brigades first requires adding the tech for building them, then after turning on spacemaster mode, go to ground unit training, select the unit type you want then press the 'add unit' button.