divorce reasons

Alsalmo alaykum,this the second time I am writing this question as I sent a letter about 2 weeks ago but did not get any reference number. I would like to know what is the Islamic ruling on: If the women (first wife) has the right to divorce her husband that has remarried a muslim doctor that treats patients that are at risk of having hepatitis and HIV. The first wife is worried that through her husband she may be at risk of getting these diseases from the second wife as she may be or may get infected in ther future. The first wife feels she is at risk from the marriage. Jazak Allah kul khair

My Sheikh! I am a post graduate student and preparing my Masters in economics. I am married to a man with lower education. He is a gentle and loving husband but he is less educated. Can I seek divorce from him due to this reason? I can accept him as a friend but not as a husband!!

Dear scholars, As-Salamu `alaykum. Is it haram for a woman to ask her husband for a divorce because he wants to marry another wife? And if she does and he divorces her, is she going to be punished by Allah for that? Jazakum Allah khayran.

Dear scholars, As-Salamu `alaykum. I would like to know, what are the valid reasons for a divorce in Islam? Jazakum Allah khayran.