So before you ask for insights realize you're not going to like the insights they give you. Another warning, don't ever give you're age again. You must come across as an adult on these forums or you will be torn apart.
First, I think that someone who wants to improve will like the insights they give them, even if they are negative. It is something to work towards, it shouldn't matter how they are presented.
Second, he never gave his age, he was talking about the age of the kids he was performing for.
Third, I agree with that last sentence completely.
laxmaster: the warmup is definately a great idea, but if you really want some advie post the "some other stuff" that will be going with it.
Also, I wouldn't get business cards made just for this occasion. If you do good, you will get another party, if you get another party, then go ahead for the cards. What would happen if you found that you weren't ready for it, but all these people had your cards?