I think the world Wanda creates is for Vision to live in. He can't feel emotions once Shuri reboots him, though he can remember having had them.
The world is made of Chaos Magic, which is fueled by emotion, meaning being surrounded by it brings Vision back to life. This world replaces the Mind Stone.
I think all the characters in Wanda's world are just NPCs, the only real people are Wanda and Vision, and those who enter this realm (Darcy and Agatha), and the assorted demons who enter Every other character is probably just in the real world. I doubt Woo and Rambeau go into Wanda's world. Darcy definitely does, though. Darcy is used as a spy by Agatha Harkness, most likely.
People seem to forget Django is the man who raised Wanda, who went without food so she could eat, that in the comics he sacrificed himself to save Wanda from her arch-nemesis, Chthon.
We will see Pietro in childhood flashbacks. I am pretty sure Wanda watched those old TV shows as an escape from her awful life.