Women covering their faces

Q: If the face of women and hands are not awrah then why is it compulsory to cover? Is it a major sin to show the face? You said in one answer that it is compulsory in this time of fitnah... Isn't it compulsory from the era of our Nabi (Sallallahu Alaihi Wasallam) when the ayah came?

Egg donation (IVF)

Q: My husband has two wifes. I have two sons while the other wife has no children. My husband is forcing me to give one of my eggs so that he can produce a test tube baby and put this in the uterus of the other wife. I am not happy with this. Is this allowed in Islam? 

Using a robotic woman's voice in apps for disabled people

Q: I want to make an app for disabled people. I want to make an app that uses text-to-speech and speech-to-text function. Text-to-speech has a robotic womens voice, so is it permissible for males to hear such a voice? Is it permissible for me to launch such app and sell.

Secondly, I want to make speech-to-text app for the deafs so that deaf can receive incoming calls, subtitles will appear, so is it permissible for me launch such an app? If any woman is calling, so her voice will be translated into text form. I think this background process will also be robotic. Is it permissible for me to launch such app?