I've been watching your post for quite sometimes, not really sure what you really want.
IF you just want to know the sale of your air time sale, you can actually accomplish that if you just put that in your menu under a different group.
Go to - Product - Product List - Add Product
Then under Group Code put down Air Time or whatever category you want for it.
Later after you end the days, you can check the report at the very bottom under Items Sales.
There you can know the total amount of your sale for the day for each group.
If this is not what you really want, then just ignore it. I might read your post the wrong way!
Regarding the department, you can actually set without table view.
Try select the table view and hit the delete button, then save it.
They just need you to input the ticket number and order number to be able to save, beside the menu of course.
Regarding the zero amount item, I got similar problem. I can close it, but I can never settle the ticket. Until I void the zero amount item, then I can settle the ticket. It does make sense, just in case you forgot to change the price for the items. Otherwise, you will loose money because of your mistake.
Just my 2 cents!
Regards,
Leon.