Is it permissible for me to name my newborn baby boy “Al-Moustafa” ?
There is no harm in naming your son “Moustafa” without using the ”Al”.
What is the ruling on the yellow discharge that comes from a woman during pregnancy?
These discharges are not menstrual blood, but they are impure like urine and break the Wudu (ablution). If the discharge is frequent, its ruling is similar to that of urinary incontinence. The woman should perform wudu after the time of each prayer, pray the obligatory prayer, and any additional prayers she wishes, read the Quran, and take precautions against impurity to the best of her ability. Using a special pad can prevent the impurity from spreading. And Allah Knows Best.
What should a person, who doubts the validity of his Wudu, or over performs it, do?
One who doubts the validity of his/her Wudu while performing it should redo it until he/she is certain of having attained purity. But, if doubt was after having performed Wudu, then he/she should not pay attention to that as doubt after the end of an act of worship does not count. This is of course in case doubt was within the reasonable limits since once it goes beyond that, it becomes a whispering of the Shaytaan (devil) which he/she should ignore as the Wudu is valid.
Is it permissible for a person to sever ties with his sister because her husband had quit prayer and done him harm?
A sister is a blood-relative and maintaining blood-relations is obligatory in Islam. As regards her husband, he should be invited to the way of Allah with wisdom and beautiful preaching.