A little bit of new info, I think it should just be the usual Famitsu follow-up on stuff from the Jump leak last week.
Doushi
They are capable of entering into contracts with multiple Tenzoku. The ideal is for them to make a contract with a Tenzoku of all four elements, but almost none of the Doushi in history have accomplished that (another plot event they've made pretty obvious or outright confirmed...).
Battle Styles
So it looks like Zestiria's arte system/controls are based on Graces' A-arte and B-arte system. For now it seems like it's just continuing Graces' concept of getting rid of the normal attack button in favor of two arte buttons though (assuming they didn't dump it to L1 or something awkward like that), no confirmation of anything like arte trees for now. This may also make it safer assume this is using CC or something new instead of TP.
Humans' Battle Style
The Circle button is for Tokugi (I think these are usually called Base Artes in English?), which are faster and more mobile attacks. The X button is for Ougi (Arcane Artes), which are better at breaking through enemy defenses and I'm guessing are more powerful.
Tenzoku's Battle Style
The Circle button is for Tokugi that can be used to attack from mid-range, and the X button is for Tenkyoujutsu (magic artes), which are more powerful and can be used from a longer distance.
Artes
Miculio can learn the attacks Splash, Violet High, Twin Flow, Kirimizu, and Taramizu.
Edna can learn Air Pressure, Rock Lance, Embrace End, Powder Snow, and Sky.