Question about MX, Braig & Isa, and Traverse Town.

[Final Blade]

So how is Master Xehanort back exactly? Is he back from the union between Ansem SoD and Xemnas when they were destroyed? And if so, where is Terra? And is that Braig and Isa returned as well. I'm more confused about if Xigbar is Xigbar or if he's now Braig.

And about TT, if Riku was in Sora's dream, does that mean Beat, Rhyme, and Joshua were in Sora's dreams as well?

 

[Sephiroth0812]

The Master Xehanort we see at the highest throne is indeed the reformed, full MX that is back.
We have no information about Terra except that he's "on MX's side right now" according to the old geezer himself. The Ultimania of DDD explicitly claims Terra's current status and whereabouts as one of the mysteries still to solve.
Exactly how MX came back as old MX is unknown as of now.

Nomura said that conditions to return as humans have been met with Braig and Isa, yet in-game the guy is constantly called Xigbar by everyone and the blue-haired dude is listed as "Saix" in the journal.
This leaves us with two possibilities: Either they are both back as humans but keep their old names (Xigbar and Saix) to show their allegiance to Xehanort or despite the conditions being met they're still truly "Xigbar" and "Saix".
In the end it does not matter much though, as unlike as with Naminé and Kairi, Xemnas and Xehanort or Roxas and Sora, there is no different consciousness and mind in the mix. Normal Nobodies like Xigbar/Braig have the same consciousness, so it doesn't really matter if it's "Braig" or "Xigbar".

Joshua used Rhyme's memories as a portal, so yes, he could also be in Sora's dreams.