In my mind I see Madotsuki to be an older teenager, maybe ranging from about 16 - 18 years old.
The people in the dream world are people that she met outside in the real world prior to locking herself away. She’s cautious to start out when first meeting people but when she warms to them it doesn’t take long for her to slip out of her shell.
I also see her sometimes retaining the effects she had in her dreams though that doesn’t happen too often.
Unfamiliar areas and large speces tend to make Madotsuki nervous, this is due to the familiarity of the Dream World and her bedroom.
Certain emotional stresses and the like will cause a complete mood shift and break in sanity in Madotsuki, she will not hesitate to kill when in such a state.