Every Blood Elf is a High Elf.
Not every High Elf is a Blood Elf.
No, but they did adopt a new culture, one that cast off the rigid shackles of the old ways, put less emphasis on bloodlines, and in which ambition, power, and strength became the cornerstones. The Blood Elves became a meritocracy where one’s abilities and deeds were the means to advancement, rather than marriages or wealth.
Ninety percent of the kingdom of Quel’Thalas, you mean. Specifically, those elves who died during Arthas’ assault on the kingdom. This figure has never accounted for elves outside of Quel’Thalas, such as those whom remained with the Alliance after the Second War, those trapped on Outland, those in Dalaran, and now whatever theoretical number of High Elves live in the Arathi Empire across the sea.
Plenty of races haven’t morphed into another race. Mechagnomes didn’t cease being gnomes. Kul Tirans are still humans. Orcs and Mag’har orcs are both orcs.
Not quite.
Old RPG lore tells us that the Night Elves never let the High Elves near their moonwells, and while the RPGs were decanonized, there was, lorewise, mistrust and suspicion from the Night Elves towards the High Elves. As such, there’s no indication that High Elves ever used the Moonwells to sate their addiction. From the comics we know the High Elves in the Hinterlands just went cold turkey, while from Vereesa’s perspective, we know High Elves in Dalaran were supplied with magical artifacts to drain in order to avoid the effects of withdrawal.
Also, the Blood Elves at large didn’t turn to fel to satisfy their addiction. The reason Blood Elves have green eyes is because fel was the fuel for the magic Rommath and his magisters used to rebuild Silvermoon City practically overnight. All the Blood Elves were exposed to fel on a large scale, which was why they developed green eyes. Otherwise, they drained mana crystals and mana wyrms.
Arcane and holy.
Maybe, but I doubt it myself. Even if that were the case, High Elves are connected to the Sunwell as well, so they too would become this theoretical, ‘new race.’ Perhaps even faster than the Blood Elves would, since there was no trace fel to remove from them first.