Hi Gene,
You will normally see 2 oz servings at most events, unless the organizer specifies some other size. Sometimes the organizer will also provide the cups so that all servings are of the same size. Might check with the organizer on this.
Keeping it toweled in a cooler would most certainly work. For serving, set up a chafer with the disposable pans in steam table pans with some form of heating source and water in the steam table pans.
Best of Luck and Enjoy !
Bob