And one minor thing, that might help speed up the complex games at set-up time: I would call what we played at TagFest a SCENARIO game rather than a LARP game, as there were really no characters per se, just a couple of players with specific jobs to perform.

So it seems to me that there is very little need for a back story -- it can simply be stated "Your goals are to ______ (fill in the blanks). The other team will be trying to _______ (fill in their major objective), and also trying to accomplish a couple of goals that you don't know about, but need to try to figure out and stop them. They will be doing the same to you. Now let's get it on!"

Is it possible to have Saturday as the adult day and all Sunday as an "open to public" day?

My schedule is quite flexible but I know a lot of my friends would have a hard time coming to an all day Friday event.

Just two more cents.