Around your waist
You would wear it wherever you would wear a tuxedo. A cumberbund is part of the formal wear attire that is an accessory to the tuxedo. & it is worn, by men, around the waist.
On or just below your waist. It should hide the top of your trousers
a cummerbund is worn below your waist. It should hide the top of your trousers.
nobody should wear a cummerbund, unless you're from the 80s.
You should always wear a cummerbund when dressed in formal attire, for a black tie event. When you wear a single breasted jacket, cover the waist with a cummerbund or vest.
You wear it over your braces (suspenders).
The cummerbund is worn around the waist, covering the waistband of the tuxedo pants and the bottom of the shirt. The pleats should face upwards.
feet
On your face
Yes, you should wear braces (suspenders) anytime you are wearing a tuxedo, weather you're wearing a cummerbund, vest or going with the exposed waist look. You do not wear a belt with a tuxedo, and this is the only way to keep your trousers at your waistline.
People wear a cummerbund. People wear cleats. People wear clogs and crocs.
The head because it is a hat.