As part of your instructrions from Vivec, it is recommended to kill all the Dagoths and retrieve their artifacts, but it's not essential to the MQ. Who listens to Vivec anyway?.. :rolleyes:

I do not remember this place. 0.o There were six ash vamps?

There's 7 ash vampire all together. Killing them all is optional. But for rp sake just go ahead and kick their butt.

Well, it's not vital for completing the mainquest. If i recall correctly, Vivec ADVISES you to deal with the ash vampires before heading to Dagoth Uhr, but it's not a must. Besides, i was assuming that all of them were spread out over Red Mountain, and i've cleared that entire region when i went on some quests for the temple. As some sort of bonus for my own amusement, this time i also cleared out all three major vampireclan bases, which is also something i'd never done before. No matter how many times i play Morrowind, i find something new every time.