Nikaah & Marriage Issues

Marrying a Christian

Q: I married a Christian girl and conducted the Nikah myself - i.e. I got two non-Muslim witnesses, asked her if she accepted my proposal based on the Mahr I gave her, she accepted and I then read the Nikah Khutbah, and confirmed that I have accepted her as well in my Nikaah. First Question: Is my Nikaah Valid? Secondly - things did not work out and I have subsequently given her 3 Talaaqs telling her that I divorce her in front of two Muslim male witnesses. If she reverts from Christianity - can I remarry her (perform Nikah again) or not? (Does she first need to remarry someone else etc.)

Secret nikaah

Q: I would like to know my friend is sixteen and he is getting married to a girl who is sixteen. He is going to have his two friends as witnesses and he will give mahr and both the boy and girl will sign a contract. They both are Muslims. I wanted to know if the nikaah will be accepted as there is no guardian from the girls side because her parents says it's to early to get married.

Illicit behaviour

Q: If a man keeps bad faith for his sister in law although, he did not practically commit anything, but shows his interest in her verbally while communicating with her. Does this effect his nikaah in anyway?