If you are going to do all this, definately do as Simon say and split it into sections. If you have two days available, speed tuning and boathandling could be one day, and starting + some short regattas for day two.
IMO you don't need 2 days.
These sessions have 2 major goals:
1, Speed
Show people that gains can be made with boat tuning - People go out for a short sail (30mins say) and go around a short course many times so everyone can see who is fast and who is slow(er), you get the "instructors" to tune peoples boats (and the people them selves - position for the given conditions etc) - easy in established classes where the "fast" numbers are already known, more difficult in development classes where "numbers" differ by builder / sails etc. But still it is possible to impove most peoples setup. You now introduce the concept of 2 boat tuning and explain how it works. The people go out again to (Hopefully) show that people are now closer in speed. Now people start 2 (or more) boat tuning and agree what setting to change for each leg etc. The main goal is to teach people how to 2 boat tune, not to make everyone 100% fast.
2, Boat handling
G+T's
Mark roundings
High and low wind kite hoists and drops
land practice; Plan out how you (and crew if applicable) do things etc.
One can be done before lunch, one after !
I think these sessions should be about giving people the tools to learn, not just learn at the session.
