I've only need to show my marriage certificate twice that I can think of. One is to change my name on my social security card. The other is give a copy to the Army for legal purposes.

I think everyone else has answered the other questions.

"You need me. You wouldn't be much of a hero without a villain. And you do love being the hero, don't you. The cheering children, the swooning women, you love it so much, it's made you my most reliable accomplice." -- Lex Luthor to Superman, Question Authority, Justice League Unlimited