A customer orders at the counter but wants to sit down and eat. Do I ring it up as a sale or open a table?

Either works, and it depends on whether you will add to it later. If they pay now and that is the end of it, ring it up as a counter sale and the kitchen ticket prints straight away. If they might order more, tap their table on the floor, add the food, press Send to kitchen, and charge the table when they leave. A table also carries the service charge if you have set one, and a counter sale never does. Both reach the same kitchen screen. The Tables, tabs and the kitchen screen tab in the docs explains tabs and rounds.