Awesome! Hope you enjoy it and the little bits of art thrown in along the way.
As for the Ardling, with them seemingly being such a sudden addition you wouldn't think they'd be common like the Tiefling, but to me it seems like they're trying to make a sorta "good" version of the Tiefling who similarily are known having ancestors from the Outer Planes yet don't usually originate from them, unlike the Aasimar who I've always presumed to be actual outsiders... but who knows, it may turn out to be the other way around. I encourage you to stick with your depiction or instead write an Aasimar if you'd be more comfortable having more material to work with.
If you'd like me to pick between a spellcaster or a more martial class, I'd prefer the former, but I love any character who knows a thing or two about casting spells. Thanks for asking.