It's a bit of an eyeball-it situation on abilities that don't have direct equivalents, so ratings will be a bit subjective. As for the following, I'd say...

Quote Originally Posted by Falontani View Post
Where would the nymph's divine grace esque ability fall?
Assuming you mean unearthly grace, this is slightly better than the paladin's divine grace, which they get at 2nd level but anyone taking this with a feat probably has a far heavier focus on Cha than a paladin. I'd say a 3rd or 4th level spell. Probably lower it slightly due to requiring both a feat and the ability to shift into a nymph, which requires further resource expenditure. So 3rd level spell, approximately.

Quote Originally Posted by Falontani View Post
Dryad's blinding beauty?
Nymph's blinding beauty, I believe you mean. Blindness/deafness is a 2nd level spell, but it has more utility while having far fewer targets. Plus, blinding beauty affects everyone, not just enemies. Meanwhile, Chain Spell is a +3 level adjustment metamagic feat that affects only enemies, as it's assumed that you won't be blinding allies, meaning the adjustment should be lowered a bit as a result. So I'd say blinding beauty is approximately the equivalent of a 4th level spell.

Quote Originally Posted by Falontani View Post
Gaze attacks? Breath weapons?
Depends entirely on what they do.