Not a big preference for me, so let's just go with your second table there.
Are we done with the mechanical parts of these?
Well, I was originally in favor of just doing one-off damage (roughly speaking), so I'll go for version #1. It just seems a little simpler to adjudicate.
If we stick to that, it looks like we're done with the mechanical stuff. Seem right to you?
We've still got to decide on the energy resistances, but I think that's the only mechanical aspect to sort out once we've finished with the Susceptibility to Darkness.
Ooops. Yes, that progression looks fine to me.
Incidentally, I think I'd prefer the save against the flash to be a Fort save, rather than a Ref save, but I guess I'm not too bothered either way.
Moving to tactics, the original text says they prefer their ranged attacks: While radiance quasi-elementals are capable melee combatants, they prefer to stay at a distance and strike at foes using their beam attacks, changing energy types as necessary if some opponents exhibit a resistance to a certain kind of energy. Against larger groups, the quasi-elementals will often attempt to disable multiple enemies with their flash.
Looks good to me!
Description: A bright, spinning ball of multi-colored energy.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.