Is it permissible for a guardian (Big brother) to unlawfully stop his sister from getting married?
If the guardian denies her right in getting married for an unlawful reason, she should go to court in order to settle that matter, and the guardian is considered sinful in this case.
Can someone who begins a voluntary fast break it?
It is preferable for someone who begins an act of worship not to break it.
Allah the Exalted has said {what means}: "and let not your [good] deeds come to nought!" [Muhammad/33].
However, if a person starts a voluntary fast (nafl) and needs to break it, they are going against what is preferable, but there is no sin upon them.
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.
Some online stores offer a discount on a customer's first purchase — what is the ruling on creating a new account each time a customer makes a purchase in order to obtain that discount?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
It is obligatory upon a Muslim to uphold honesty in both his words and his actions. Allah the Almighty says {what means}: "O you who have believed, do not betray Allah and the Messenger or betray your trusts while you know." [Al-Anfāl/ 27] And He says {what means}: "O you who have believed, fear Allah and be with the truthful." [Al-Tawbah/ 119]. And the Messenger of Allah ﷺ said: "Whoever deceives us is not of us." (Reported by al-Bukhārī.)
As for creating a new account for the same buyer, the terms and conditions of the website must be observed and respected. If doing so violates those terms, it is not permissible. And Allah the Almighty knows best.
