1. Is there a sexual act/position/practice that you were sure in advance you would hate (or never try) and then discovered to your surprise you loved?
Nothing comes immediately to mind. Mind you, I haven't experimented a whole lot. My opportunities have been somewhat limited.
2. Is there a sexual act/position/practice that proved a lot less interesting in practice than you thought it would be beforehand?
Not yet. See my previous answer.
3. How do you let your significant other know you're in the mood? How do you let a new person in your life know?
The first question isn't applicable to me; and the second I'm not sure I have an answer for.
4. How does your significant other let you know he/she is in the mood?
Not applicable to me.
5. Is there one that got away - a sexual opportunity you didn't realize was one at the time, or weren't ready for and regret missing ever since?
Not a sexual opportunity. I can think of one opportunity-not a sexual one-that got away, but I couldn't have acted on it anyway. I probably would have been too young to appreciate it as I would now anyway.