2. The real daughter can maintain a blood brother/sister relation or she will become non-mahram too?
بسم الله الرحمن الرحيم
(1) Mutabanna (an adopted son) is not in place of real son. Hence after he becomes adult and the child is not mahram of the woman who has adopted him then the adopted woman will be like a strange woman for him and it shall be mandatory for her to observe purdah from him.
(2) No! the adopted child is not in place of real son.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.