Kevin...what you have described sounds good and is pretty much what we are doing and going to do with a group of Air Force Junior ROTC cadets.
There is a "ground school" (your's, by nessessity, will just be shorter in duration ) where you can give a brief discussion of the dynamics of flight. A short demo with the airplane sitting on a table and the radio on will show them what does what...you already have that in mind so...
They always ask the same questions: "How fast will it go?" (I took my WM Dago Red to "show and tell" and got a few oohs and ahs ) How high will it go, what's the range, how much $$$ does it cost, etc etc.

Do you have someone to act as "announcer" with maybe a P.A. system or even a bull horn? A set routine of manuvers called out beforehand (like the Blue Angels/ Thunderbirds ) makes you look more professional. And you can have a "freestyle" section of time too of course...
I have put on demo flights at several schools, and getting a feel for the area before hand can make for a better and safer demo. I like to check things out in advance first, like for wires, trees, not flying over houses, etc. etc. etc.
Crowd control is very important of course. Where will you be flying? I have flown in football and soccer fields (one in the same in europe, aye?) and we had the students in the bleachers...

If you want a little P.R. for your club, maybe call the local newspaper and they might do a write-up/ photos on your "civic mindedness"