What is the ruling on wiping the white area behind the ears instead of wiping the head?
The obligation in ablution is to wipe some of the head; it is not a condition to wipe all of it. Wiping the white area behind the ears suffices for that. And Allah the almighty knows best.
Is the marriage contract considered valid if concluded at home by the marriage official (Ma`zon)?
Yes, it is valid as long as it is registered at the court.
Is it incumbent on a husband to pay the alimony of his wife if she had left him and stayed at her parent`s without his permission?
When a wife leaves her house, and stays at her parent`s without asking her husband, she is considered a Nashiz (wife who refuses to abide by her husband’s orders), and so she doesn`t deserve an alimony.
The Prophet ﷺ said: "There will emerge from my nation people who will drink the Qurʾān as they drink milk" — is this ḥadīth authentic, and what does it mean?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
ʿUqbah ibn ʿĀmir, may Allah be pleased with him, narrated that the Messenger of Allah ﷺ said: "There will emerge from my nation people who will drink the Qurʾān as they drink milk." (Reported by al-Ṭabarānī in al-Muʿjam al-Kabīr, and cited by al-Haythamī in Majmaʿ al-Zawāʾid, who stated: "Its narrators are trustworthy.")
The meaning of this ḥadīth is that there will emerge from this blessed nation people who recite the Holy Qurʾān without reflecting upon its meanings or pondering its rulings — the noble verses passing over their tongues just as milk passes over them when it is drunk, leaving no trace of thought, understanding, or contemplation behind. [See: al-Taysīr bi-Sharḥ al-Jāmiʿ al-Ṣaghīr,Vol.2/P.63] And Allah the Almighty knows best.