There've been a couple Posts about tweaking the production modifiers for population levels (to give even higher bonuses for those ringworlds and sphereworlds). I'll see if I can bump them back to the top of the forum
Also, happiness affects production too; I think there's a 20% bonus for Jubilant (usually spelled "Jubiliant" in the game, but I think they're fixing it in the next patch), and steadily decreasing bonuses for the other happiness levels. I think angry actually has a production penalty (-5% or -10%), but I'm not certain. I think you also get a reproduction increase for higher happiness levels.
Oh - and the only time I've seen Deadly conditions is as the result of an Intel operation (or one of those "Random Events").