About the drinks.
It is tempting to go the cup of ice and fountain pop route for economy reasons but in the long run they are more of a PITA than they are worth.
1. Keep sanitized
3. You ALWAYS end up having to switch canisters in the middle of service.
4. The ice ALWAYS melts before the last delivery.
IMO would carry a good mix of drinks, 5 or 6 of the usual (bottled/canned) suspects plus a handful of small batch offerings (root beer and cream soda for instance) as well as a couple of types of water both spring as well as something like this http://www.sanpellegrinofruitbeverages.com/us/en/default.aspx and keep them coldcoldcold (or stick them on ice for delivery).
Can you tell I like openings