Is it permissible for the young woman to turn the suitor down if she had no feelings for him?
Yes, it is permissible for her to do so.
By slip of the tongue, my son cursed Allah. It is worth pointing that he has concluded his marriage contract recently, but haven`t consummated the marriage. What is the position of Sharia on this?
All perfect praise be to AllahThe Lord of The Worlds and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions.
This person must return to the fold of Islam by uttering the two testimonies of faith and making repentance to Allah from all acts that lead to disbelief. Also, he must make a new marriage contract because the old one was dissolved after he had committed this act of disbelief. Moreover, since there is no waiting period for his wife, then she is in state of Talaq ba`en baynona Soghra (Minor irrevocable divorce); consequently, she can get back to him only by a new marriage contract. And Allah The Almighty Knows Best.
Is it Permissible to lighten the eyebrows (I.e. Dye them blond)?
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.
Lightening the eyebrows is applying dye to them, and it is permissible to dye hair with other than black. The proof of this is the Hadith related by Muslim on the authority of Jabir told that when Abu Quhafa (Abu Bakr’s father) was brought on the day of the Conquest of Mecca with his head and beard white like hyssop, the Prophet (PBUH) said: "Change this with something, but avoid black."
However, it isn`t permissible for a Muslim woman to show her ornament (Zeenah) in the presence of non-Mahram men (Men permissible for a woman to marry). And Allah The Almighty Knows Best.
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.