I got the first quest in his series on my monk at lvl 14 even though he says 15+ .... did all the quests.
I was 26 by the time I finished his last quest in his series. Got the aug as my reward.
He will NOT let me repeat his series. He just tells me he's glad I solved his mystery for him.
This contradicts the quest information for all of his quests here which say the series can be repeated. I'm not killing myself to 15 to find out if my level is the problem.
I searched all over for this guy but could not find him. Final at level 20 I got track and located him. He is in the loft above the brewers. You can use find for Brewermaster Teremun to find him.