yes but it do not need to be there
No, you do not need a license plate for a bicycle.
Motorcycles have mounts (on the swing arm orunder the tail light), if it is a pedal bike, most are just zip tied to the bottom of the seat.
take off the license plate then screw the holder on with the plate.
Yes
on the bumper?
Yes you can!
yes
Yes, in Wisconsin, a 50cc scooter requires a license plate. Any motorized vehicle that can exceed 30 miles per hour and is not classified as a bicycle must be registered and display a license plate. Additionally, the operator must have a valid driver's license or a motorcycle endorsement to ride it legally on public roads.
If you're asking about where to put your sticker on the license plate than that would be the rear plate.
Probably
You put a sign in the license bracket "in transit"
If it comes with a plate mount it will be under the rear of the seat or by the back mudguard (if equipped).