Yes... Perhaps once...everyone can make one mistake. More than once...no.
Yes, if it was a casual "dinner and a movie" date and he wasn't in a relationship with someone.
Date as in a one-night stand? Sure
No, as in have a relationship. I don't do one night stands.
I do because my bed is against the wall in the other side.
While I know some cheaters who did it only once and are extremely loyal now, I have trust issues. If I know they did it once, I'm not sure I won't have any doubt in the back of my mind. It's not logical, I can't really explain it.
No. That's just a dum thing to do.