Is the son of the sister by breastfeeding considered a mahram in Islam, and is it permissible for a woman to go for Hajj with him?
Everything that is prohibited by lineage is also prohibited by breastfeeding. The son of the sister by breastfeeding is considered a mahram, just like the son of the sister by blood, and it is permissible for him to be her mahram for Hajj and Umrah. And Allah Knows Best.
I am an author, and I have books stored with me. Is it permissible to pay my zakat in the form of books containing beneficial knowledge for poor students, such as chemistry and mathematics, or religious books that spread Islamic sciences?
Zakat on wealth must be paid in cash from the wealth itself. Therefore, you should pay your zakat in monetary form so that the poor can purchase what they need. And Allah Knows Best.
After I was ran over, I had cracked ribs, concussion, a tension pneumothorax, and retired as a result. What is the amount of the Diya?
All praise is due to Allah the Lord of the worlds. May the blessings of Allah be upon our Master and Prophet Muḥammad and his pure progeny.
What you have mentioned requires a detailed medical report since the benefit of every organ that you have lost deserves a full Diya (In Islamic law, Diya is the financial compensation paid to the victim or heirs of a victim in the cases of accidental murder, bodily harm or property damage). Moreover, the decrease in the benefit of some organs has to be assessed by expert doctors and allocated a percentage from the Diya accordingly. Therefore, we advise you to refer the matter to the courts or reconcile with the driver and forgive him so that Allah may forgive you. And Allah The Almighty Knows Best.
I took a car from the Orphans' Fund Development Institution; is there usury (Riba) involved in this transaction?
If the Sharia's conditions were met, then there is no harm in this. And Allah The Exalted Knows Best.