Re: Microwave oven
If the micro has a dedicated location, like a niche in a cabinet, is built in or, is an over the range combination hood unit then yes, it gets a circuit.
If on the other hand it is just another loose appliance used on the countertop then, it's just like a toaster or waffle iron, it does NOT need it's own circuit.
The countertop gets two 20A circuits of course.