if i have a Tyrian (phrophecies) character and move this character to Cantha and complete the "Nahpui Quarter" ascension quest, do i still get the 50000 experience for getting ascension?
No - you get the XP for beating your doppelganger at Augury Rock, not for any other method of ascension. Furthermore, completing Nahpui Quarter (or Hunted! in Elona) before Augury Rock means that you will never get those 50k XP.
Hmm all that trouble for survivor when you have vaettirs makes this a strange choice imo.
True, and some players buy hammers, and some go boxing, and some just go for the skill hunter titles to do it.....but some players still like the challenge of getting the title through normal play.