Sunnah method of dua after fardh Salaah

Q: What is the correct manner of reading the dua after Salaah with regard to reading it loud or soft. Should the dua be made audible (loud) or inaudible (soft)? In our musjid the Imaam starts the duaa loud and reads the first part loud then remains silent and reads the duaa silently, thereafter he reads the ending of the duaa loudly again. Is this correct or is it a bid'a?

Using black dye

Q: I am a 21 year old girl and my original hair colour is black, last year I did colour it blond and now its looking bad like two hair colours. I am also married. I heard that its not allowed to colour hair black in Islam. Is that true? If yes then why? I just want my natural hair black and I can't trim it either.

Travelling without a mahram

Q: I live in China and I have to work here till February next year insha Allah. My wife is pregnant and its becoming difficult for her to manage here alone and she wants to go back to India for the delivery of the child, the reason being her loneliness and bepardagi (Hijaab) because of male doctors. Its expensive for me to go with her and then come back and join my job here in China. Is there any relaxation in sending her alone through some direct airline? I would take her to the airport in Burqah and she will be picked up by her relatives there in India. Can my wife travel alone?