Do you agree to marry a man who is already married, has children, and smokes, while you detest smoking and fear injustice to the first wife and children, and he says he needs a wife to help him with matters of his religion?

A man who is pleasing in his religion and character is the goal and aim for a Muslim woman. People vary in this quality, and one should seek the most complete, then the next, down to the one who is outwardly decent (mastur al-hal), meaning one who is not known for open transgression. It is permissible to marry a transgressor (fasiq) - one who commits major sins or persistently commits minor ones - but he should not be accepted if there is someone better than him. Perhaps accepting him is better than spinsterhood, especially at this late age, and she should try to reform him, for perhaps Allah will reform him through her.