Is it permissible to swear by (Allah "The Living")?
Yes, it is permissible because "The Living" is one of Allah`s Attributes.
Can the Christian widow whose married from a Muslim become an heir of his?
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.
A Christian widow can`t inherit her Muslim husband because their religions are different. And Allah The Almighty Knows Best.
Is it permissible for my brother, whom I had suckled, to conclude a marriage contract between his daughter and my son?
Such marriage is impermissible since one`s nephew in this situation is considered an uncle to one`s daughter; consequently, he is the brother of her father by suckling. In such cases, the people in question should go to court to prove the suckling.
Does touching women temporarily forbidden in marriage nullify ablution?
It is prohibited to touch, or to shake hands with such women as they are considered strangers, and doing so nullifies ablution.