That said, I think you are being much too direct and shortsighted in what you are trying to do. More subtlety is needed here. Look at it from the priest's point of view: he has a program which is dysfunctional, but working to some extent. Now someone comes in proposing to make big, controversial changes. If the priest has only just met you, he has no idea whether you are seriously committed to what you are discussing. Talk is cheap. You could get in there, really stir up a hornet's nest, then leave in a huff. The parish would be even worse off. It is his duty to protect the parish from unecessary scandal.
Here's what I suggest: get in charge and be real quiet for a while. Be very incremental in trying to improve the situation. Pick individual things to get improvement on over time. While you are doing this, try to develop relationships with as many of the kids and parents as possible. Charity is key here. Remember that you are trying to help these kids worship properly. Yelling at them and expelling them is not going to get them to love God more or worship better. The longer you are in the position, the more power you gain, by demonstrating your committment to the work.
Concentrate especially hard on traing new servers. It is likely that you will eventually solve this problem by the older, irreverent, servers aging out. Also, never forget that some of those older servers may truly want to do better up there. They can be your allies.
I guess my main point is that you cannot make things turn on a dime. Be patient and committed to long term change. Work toward your vision and pray alot about it. Remember to cover all with love for God and for the kids you are leading.