What is the ruling on buying a car from someone for less than the market price, because they are in a hurry to travel and want to sell their belongings at a lower price due to their urgency?
Yes it is permissible; however, a Muslim shouldn't take advantage of other's difficult situations.
What is the ruling on someone who vowed to fast for two consecutive months, but failed to do so?
He is obliged to fulfill his vow by fasting for two consecutive months, but if he fails to do so then, it remains a debt on him until he either fulfills his vow, or dies. In case of his death, his guardian is supposed to fast on his behalf, or donate food from his estate in return for fasting, but if the guardian fails to do so then, it is all in the Hands of Allah.
After a month and a half from the end of postpartum bleeding, my wife occasionally finds a small amount of blood, and she is breastfeeding. What is this blood, and should she fast and pray when she experiences it?
This is postpartum bleeding, so she should not fast or pray until she sees the signs of purity, unless it exceeds sixty days, as the maximum duration for postpartum bleeding is sixty days, and the majority of women experience forty days. If it exceeds sixty days, it is considered irregular bleeding (Istihada). It would be advisable to consult a doctor after the sixty days. And Allah Knows Best.
Is it permissible to have sexual intercourse with pregnant wife?
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
There is no sin in having sex with one`s pregnant wife as long as there is no medical condition preventing her from that. And Allah The Almighty Knows Best.