I only have a cold light, so don't know about the first part, but that's interesting.

As for the blue light, I guess it wouldn't matter much for fixed grade paper and might matter very slightly for VC paper, since no lens is perfectly achromatic. I'm not sure how much UV or violet light gets through an enlarging lens ( and film! ), probably not much, but it might make more difference up at that end of the spectrum. Maybe someone has done a calculation to show that these aberrations are smaller than the "CoC" or grain size on paper....