I'm grinding the Vanguard quests. If Vanguard quest has a quest NPC that must be killed (such as Countess Nadya) in order for the quest to move on to the next stage, will she still respawn if you re-zone AFTER you have killed her? Or do you need to quit and restart the entire quest?
Second question is about level 20. I PVPed a bit and I noticed the xp bar still increases when you are 20. Any purpose to that?

Thanks!