if you become eligible for the quest The Conquest Pit do the first one normally.
but the 2nd one. The conquest pit: mad furbolg fighting can get you good xp in a short amount of time.
here's what you do.
get an 80 friend who is decently geared.
accept the fighting furbolg quest.
have the 80 kill the furbolg while avoiding the firenova totem(it hurts).
when it's dead, abandon quest and accept again.
you do not have to tag the mob, it comes 'pre-tagged' for you.
i was getting 4.5k-9k(rested) xp per kill. and it took 30 seconds or so to kill him for my rogue friend.