The Tillers

Are these direction quests for Yoon live? I just started his chain till I noticed he ends these (this and the Horde version) breadcrumb quests as well. However, they have no quest starter, seem not to be live? Anyone have a definite answer on this?

EDIT: the quest starter has now been added and is among the faction representatives in the Shrines in the Vale of Eternal Blossom. The quest is not available to me and is likely not when you do the first quest given to you by Yoon in the Valley of the Four Winds; anyone with cooking and passing by Halfhill will likely have done this quest before they are 90 and at their faction shrine, making this one of the few representative quests that is kind of obsolete.

This quest does exist on live, but is very hard to get.

It requires level 90, but at level 85-87 everyone gonna pass through Halfhill and very likely has contacted with someone of the Tillers. Apparently if one has completed the next step A Helping Hand one is unable to get this quest. In addition, it's likely (needs to be confirmed here) that either So You Want to Be a Chef... or "discover Yoon's farm" or both are semi-exclusive to this quest
-- the "semi-exclusive" means that if you have done you wont be able to get this quest (no yellow ! ), but if you have accepted this quest (in your Quest Log list) before you have done, they wont affect each other and can be done in any order.

While this assumption needs to be verified, I can confirm that if you carefully keep yourself away from anyone of the Tillers, particularly those in the market, until ding 90, you will be able to see this quest downstairs of the Shrine. You can discover Halfhill and use its flight path though.

The quest IS NOT available to my Demon Hunter, and he never did anyhing in Pandaria.
If it really exists, there must be some other requirement / restriction.
I don't think there is max level restriction, at least Wholly addon doesn't show it.