Making dua for a friend

Q: I have a very close friend of mine. Due to some personal reasons, I am feeling like as if someone has done some magic on her. I wanted to ask about some dua as told by Nabi (Sallallahu Alayhi Wasallam) or mentioned in Quran to get a solution for it. Furthermore, I wanted to know whether it is alright to recite this dua even if we doubt that somebody is under the influence of magic? I wanted to confirm this.

Dyeing the hair

Q: I had confusion in hair colouring. I am twenty years old and I have slight brown hairs which I want to dye and turn it into fully brown colour hairs. Please let me know if it is permissible?

Living with one's wife abroad

Q: I am working abroad and I would like to call my wife here. My father passed away and I have four younger brothers in the house with my mother and wife. All brothers are studying. My wife takes care of all. I can't stay here without my wife. I need her mentally and physically. In this case if I bring her here, will it cut off my mother's rights and will Allah be angry with me? What will be the Shar'ee hukm regarding this?

Zakaat on inheritance which one received after several years

Q: We inherited some jewellery from our parents, which was in the locker and after dad's death, we lost the access to the locker. Until recently we managed and weighed all jewellery and distributed among ourselves (we are four brothers and a sister) as per shariah. As no zakaat was paid on them since the father died, immediately two weeks after the distribution, my elder brother died. He didn't pay any zakaat on them. He had one wife, one son, three daughters. Are they supposed to pay zakaat for that unpaid 7 years period , and how shall they distribute among themselves?