"Is Glorfindel a Vanyarin Elf? Or a Noldor?"
He's an awesome Noldo!
"Why he has a golden hair? Or blonde?"
It's true that most of the Noldor were dark-haired, but not all. This could relate to...
"Is there any explanation of Glorfindel's parentage?"
Not yet! All we know so far is that he had some sort of
"kinship with Turgon" (JRRT, Glorfindel text II), noting that Turgon's daughter Idril was also golden haired, in any case, with Vanyarin influence.
"Is Glorfindel one of the First Borns?"
It's never said either way.
If one chooses to employ a text called
The Awakening of the Quendi (an
Elvish fairy tale mixed with counting lore) as "historical enough" to rely on here, the Elf-father
Tata (his name means "Two") first chooses 9 pairs of Unbegotten Quendi for his companions. Later he chooses again, adding 18 pairs of Unbegotten
Elves:
"and they were tall and dark-haired and strong as fir-trees, and from them most of the Noldor were later sprung." JRRT,
The Awakening of The Quendi
Not that that necessarily helps with Glorfindel! But that's how the fairy tale goes anyway
We just don't know much about Glorfindel's ancestry yet. Some have speculated that he must be from the
House of Finarfin, given his golden locks and a description in Appendix F about Eldarin hair, but I interpret the Appendix F reference to allow for exceptions among the Eldar (being dark-haired) even outside the notable golden house of Finarfin.
"How old is Glorfindel until the time he died at the Fall of Gondolin?"
Alas or huzzah (depending on if one likes some
mystery here or not), to date, his year of birth is unknown.
"How old is Glorfindel from the time he was resurrected until The Fourth Age?"
Glorfindel was restored to incarnate life (after his purging) somewhere between SY 510 (Fall of Gondolin) and SY 590 (End of
First Age) if I recall the
dates correctly...
... plus the Second and Third
Ages. I don't have enough fingers and toes for that kind of math.
