A pious man proposed to me and my father was hesitant in this regard because he is black, am I sinful if I accepted his proposal?
If the suitor is pious, color isn`t a drawback. However, try talking to your father kindly, so that he approves of your marriage with contentment, and that is better for you.
Is it a condition for I‘tikaf to be performed in the mosque?
Yes, for I‘tikaf to be valid, it must be performed in a mosque. I‘tikaf is not valid if performed at home or elsewhere.
Who is the "Capable Person" for whom the Udhiyah is prescribed?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
The Capable Person (Al-Qadir): is the one who possesses wealth in excess of their own basic needs and the needs of their spouse, children, or anyone they are responsible for supporting, during the day of Eid and the three days of Tashreeq; as this period constitutes the designated time for the sacrifice. And Allah the Exalted knows best.
What is the ruling on preparing food for someone who is not fasting in Ramadan?
It is forbidden to prepare food for someone who is breaking their fast without a valid excuse in Ramadan.
Doing so would be assisting in sin, and assisting in sin is itself a sin.
Allah says {what means}: "but help ye not one another in sin and rancour" [Al-Mai`dah/2]