I had an experience recently with an allied race that kept giving me their sensor designs every time they updated them (at least once a year).  It annoyed the hell out of me because I kept having to flag some dozen designs obsolete whenever they did it, so I gathered my forces around their homeworld, declared war, and swiftly put an end to their shenanigans.

Point:  Apparently they sometimes share technology.

Whenever two (or more) empires have colonies on the same body, technology 'spill-over' occurs - that is, obsolete (two or three levels) lower versions of any newly-researched technology is shared with your neighbours.

I don't know. They are definitely NON-industrial. Are they supposed to be generated with no facilities of any sort?

hahaha that funny going to war because some race is sharing technology, or atleast obsolete tech that is causing paper work issues.

Every race has ratings for xenophobia, diplomacy, translation skill, militancy, expansionism, determination, and trading skill. These affect how they act and how your relations progress. If you create a diplomacy team and assign it to that race, it will improve relations (I think by its skill level each year). You can eventually work your way up to allied, but that basically means you can move through their systems and maybe use their facilities without making them mad. Somewhere here or on the wiki is a pretty good explanation of how this works.

I was curious so I SM-ed myself a large invasion force and attacked the planet. Turns out they had a pop of 1.8 billion and absolutely no facilities. They were also curiously passive; I dropped troops and they still didn't go red until I attacked them. They gave me 613k war reparations. This was either their homeworld or a perfectly terraformed (huge) colony, as it fell right in the center of their environmental tolerances.

This seems like it might be a bug in the game, so I'll report it in the bugs thread.

Edit: Now that I think about it, maybe they weren't strangely passive, they just had no idea I was there until I started shooting at them. With no detection facilities or sensors, I guess everyone else is invisible until they make themselves known.

I'm going to have to figure out how to play this without making the game no fun. This is a big, juicy, easy to pick plum. I don't even need drop ships to land troops; they can just walk out the hatch onto the planet with no danger. Or, I could exploit the rest of the system and they would never know, like they were a no-tech race. Feel free to make suggestions.

Actually, even with a temperature of -36C, it can be a homeworld, since NPRs can be generated on planets with temperatures of as low as -40C.  I think C101 does mean 101 ground combat strength, but I'm not 100% sure.  As for why the EM is much more higher than that of Earth's 1 billion while their thermal temperature is so low. . .  No idea.