Those women with whom nikaah is permissible

Marrying a woman who was married to a non-Muslim

Q: I know a Muslim female who married a non-Muslim and now she has a 15 years old son. Now she wants to marry a Muslim. What about the son? If she wants him to be a Muslim and he does not accept then, what's the ruling in Islam. Also is it permissible to marry a woman who can't give birth to a child? If she did not marry a Muslim, there is a great danger to her Imaan. Can I marry her even if she is 15 years older than me? Please guide me in this regard.

Taking a second wife

Q: My question is if a person has been forcibly married by bribery and blackmail and then later has accepted the nikaah and has treated his wife with loyalty, can he get married again in a second nikaah? Can he do a second nikaah while still married to the first?