2) That's a bit annoying. Honestly I'm could care less about the energy output, I just want to process the uranium -> plutonium -> MOX -> RTG pellets and the 50% output also seems to mean it takes 2x as long.
the exact maths isnt know to me but it seems to be around 2-3x more heat at 70% coretemp than at 0%. someone with knowledge of the code might nip in and lay it out in numbers i hope.
At 100% heat it would produce 5x more energy, and it scales down from that.