Curufin is meant to be a dead ringer for his father. I think we should decide on the actor for Fëanor first.
Also, while the Sons of Fëanor will be appearing this season, I don't think we're casting them until next season. Curufin is unlikely to have any lines in Season 2.
Curufin is, admitedly, a piece of work. But is he really a Ramsay Bolton level piece of work? He gets his father's ability to convince people of things, and not usually good things....but he wasn't the ringleader until Nargothrond and the Beren story. He seems to have gone along with the kinslaying at Alqualondë and the burning of the ships afterwards, but these weren't his handiwork.
Abandoning Finrod to his death and the attack on Doriath come down to him and Celegorm (and he is the brains of that operation). Until that point, I'm not sure how unsavory he is. Brutal, yes, but not needlessly cruel nor the most arrogant of his brothers (here's looking at you, Caranthir).