Pandaren Ambassador is an achievement for getting exalted with all nine Pandaren factions, also with reward wow mounts from every faction and the relative transmog gears, Recipes.
Pandaren Kite String - Achievement reward, it is a flying mount like many flight mechanisms in most Flight Paths of Pandaria.
The nine factions reputation can be exalted by doing daily quests or props.
The Lorewalkers: Players gain reputation with The Lorewalkers by visiting monuments, completing achievements, and hearing folktales.
Tushui Pandaren(Huojin Pandaren): Many classic dungeons will give you rep for this faction if you are wearing the tabard.
Order of the Cloud Serpent, The Tillers, and The Anglers reputation are easy to gain, only need to do daily quests every day.
The rare elite Zandalari Warbringer will drop Stolen Klaxxi/Celestial/Golden Lotus/Shado-Pan Insignia, which Grants 1000 reputation with the specific faction. There is also a chance to drop wow mounts and a large number of materials in MOP. 
Players can buy tokens of Klaxxi/Celestial/Golden Lotus/Shado-Pan which can 100% increase rep from NPC when faction reputation at Revered. Do not forget to use this when revered.