Regarding the pickup time / prep time.  You'll want to set the prep time to the closest accurate measure of how long the restaurant on average takes to prepare the orders that you send them.  When you are sending an order to a restaurant it will recommend a pickup time to establish.  This pickup time value should be based on NOW + Prep Time for the Restaurant = Pickup Time. 

When you are clicking "Send" on an order to send the order to the restaurant, you have the chance there to update the PickupTime value based on any situational affects.  This number should be set as a Time Value such as 4:45PM.