Avi K.
I dont think you are correct about a Cohen marrying a convert. I know such a person . The woman had actually converted Reform and they got married. Later on the woman decided she wanted to become more religious and converted Orthodox. They were not forced to divorce. He is a Passul Cohen and their children are not cohanim. They do not have a Ketubah, but remain married (They are both religous as are their children and grandchildren)