What is the Islamic ruling on parents asking son to divorce his wife?

Praise be to Allah the Lord of the Worlds.

If their asking him to do so is justified in Sharia, then there is no blame on him to obey them. And Allah The Almighty Knows Best.

Is it permissible to fast on behalf of the dead who died owing missed fast to make up?

His relative should fast on his behalf, and it is permissible for the guardians to give permission to non-relatives of the dead to fast on his behalf as well. And Allah Knows Best.

Does bleeding from the body, such as from wounds, invalidate ablution?

Bleeding doesn't invalidate person's ablution. And Allah Knows Best.

What is the ruling on the financial leasing transaction in commercial bank?

Any transation that is involved in the unlawful is impermissible. And Allah Knows Best.