How should I deal with the whispers of the devil with regard to ablution and purity?
Whispers in ablution are from the devil, and so you should take refuge in Allah from the devil`s evil suggestions that aim to distort the religion. Thus, once an organ is completely pure, don`t question its purity since having whispers doesn`t mean that the purity is invalid as it has already been established.
Is it allowed for a Muslim woman to wear nail polish?
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.
Nail polish is an adornment that a woman is allowed to wear for her husband, and not in the presence of non-Mahram men. However, during ablution water needs to reach the nails, so it isn`t possible to perform 'Wudu (ablution) with nail polish on. Therefore, it isn`t valid to make Ghusl Jnabah (Ghusl performed after sexual intercourse or ejaculation), Ghusl after menstruation and Ghusl after Nifas (blood of childbirth) while wearing nail polish. And Allah The Almighty Knows Best.
Is it permissible for the young woman to turn the suitor down if she had no feelings for him?
Yes, it is permissible for her to do so.
What is the ruling of Sharia when a man releases his sperm out of his wife`s vagina?
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.
This is called coitus interruptus and it is permissible according to Sharia when practiced by agreement of both spouses. And Allah The Almighty Knows Best.