RE: Elrond/ next high king of the Noldor.

[Raynor]

I agree it was an usurpation:

Originally Posted by Concerning Galadriel and Celeborn, Unfinished Tales

Sauron used all his arts upon Celebrimbor and his fellow-smiths, who had formed a society or brotherhood, very powerful in Eregion, the Gwaith-i-Mirdain; but he worked in secret, unknown to Galadriel and Celeborn. Before long Sauron had the Gwaith-i-Mirdain under his influence, for at first they had great profit from his instruction in secret matters of their craft. So great became his hold on the Mirdain that at length he persuaded them to revolt against Galadriel and Celeborn and to seize power in Eregion; and that was at some time between 1350 and 1400 of the Second Age. Galadriel thereupon left Eregion and passed through Khazad-dum to Lorinand, taking with her Amroth and Celebrian.