My husband told me that he concluded our marriage with a fake name that belongs to another person, because he was sentenced. Nowadays, he brought an ID, passport and birth certificate with the his current name. What is the ruling on being married to him?
praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions.
As regards being married to the person mentioned in your question: The marriage is valid so long as he was the same person your guardian concluded the marriage with, even if he changed his name i.e. if your marriage contract was concluded with the same person, since what counts regarding marriage is the persons not names. And Allah Knows Best.
Is Aqeeqah due on the miscarried embryo?
No Aqeeqah is due on the dead embryo.
Am I permitted to perform more than one prayer within single ablution?
You are permitted to pray as many as you could within one ablution and to recite Quran so long as your ablution isn't nullified.
Is it permissible for one to give the Zakah(obligatory charity) to his indebted brother?
It is permissible for one to give the Zakah to his indebted , or poor brother.