Darnus is Elezen... you can see it in some videos when he uses emotes. That are the same Emotes like elezen have.
It's said that as Naels father died he replaced him. But he is also a mysterious man... anyways I don't think he is a grandpa lol
And the Garlean would never send children to sharlavan to study there...
The Garleans are too proud on thier own technology >_>
I also doubt the Sharlavan ppl would allow garleans to study thier lol