How far is "too far" when routing traces for crystals, and how asymmetrical is "too much"?
The idea behind simmetry of crystal connections is that they would pick equal amount of EMI and majority of it would be cancelled out. As it was mentioned, in low-power application crystal is driven as weak as possible, so it might be very easy to disrupt it's generation.

32kHz crystal is the most sensitive.

Also, please add to your points that you need exactly 1 connection point from GND to caps. You cannot connect them to ground wire/plate in different places, because then current flowing on the ground wire/plate will generate non-compensated noice on the crystal.