Elves to Eldar?

[lindil]

Eldar only applies to the Elves who at least started upon the great journey.

JRRT himself often referred to Elves as a whole race, even after the designation of Eldar became [ more or less fixed].

As for changing Feanor, JRRT left it that way because he wanted to reflect the Beleriandic/Sindarin 'filter' if you will through which all of the tales of the First and prior ages came. Feanor was the way his name was spoken in beleriand, even though, ironically enough, it was probably only done so after he died.

Faenor was the correct Sindarnized spelling.

yes but if I recall correctly, it was not what was ever used.

It also seems odd to me that Maedhros, when translating Maitimo would use the S letter instead of the P, so soon after his fathers death. Anyone know why?

nope