Nikaah & Marriage Issues

Using a Sheath during Intercourse

Q: I am aware that oral sex is Makrooh.  I have recently come across an article(western health website) stating that impurites from private organs could be dangerous and one should avoid these coming into the mouth. The article suggested using a sheath (alternatively dental dam) to cover the private area of a women before doing such acts. If one does take the above precautions, will the act be permissable?

Nikaah in the Presence of Witnesses

Q: A certain brother wishes to know if his nikah performed in the following manner is valid. In the presence of two jamaat brothers and his wife they first reverted his wife to Islam by making her recite the kalimah tayyiba. Thereafter he told her that I have accepted you as my wife and she also accepted him. There was no formal discussion of mahr. Thereafter they had performed their marriage at the home affairs according to the Christian Law for purposes of citizenship etc. His wife now doubts as to whether they had been living in sin all the time. Please assist.