Is it permissible for a father to disinherit his disobedient, alcohol consuming son and his daughter who had fled home and never returned?
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.
It is permissible to give heirs some money because of their being extra obedient or needy. As far as inheritance is concerned, it is to be divided after one`s death, so it had better be left to the court itself. And Allah The Almighty Knows Best.
Are minors(persons under the age of puberty) obliged to fast?
A male under the age of puberty isn`t required to fast, but his guardian should order him to fast if he was able to endure the hardship until he gets used to it.
Is it permissible for the woman to use her mobile phone while on the street?
Modesty should be observed by the woman at all times, so she is free to use her phone while on the street as long as it is done within the limits of Islamic manners.
What is the ruling on performing voluntary prayers during official working hours?
There is no harm if there was break time during official working hours, but if not then it is impermissible. And Allah Knows Best.