A woman committed adultery with several men and gave birth to a baby. Who is the father?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
The adulterers must be punished as prescribed in Sharia for they have incurred the wrath of Almighty Allah. Therefore, they must hasten to make repentance and ask Allah for forgiveness. However, the child born out of this unlawful relation is attributed to the mother. And Allah The Almighty Knows Best.
When is Istikharah (guidance prayer) Du`a offered, before Tasleem (saying asalamu alikum warahmatu allah wa barakatuh to end the prayer), or after it?
It is offered after Tasleem.
Is it incumbent on a family to provide for its old handicapped son and take care of him?
The family and relatives - e.g. brothers - of such a person are obliged to spend on him and take care of him if he didn`t have money of his own.
Should missed Sunnah prayer be made up?
Making up missed voluntary acts of worship is from Sunnah.