Motorised scooters/Go-peds

Questions:

• Are vehicles such as electric scooters/bikes, quads, go-peds, mini-motos, hoverboards and Segways legal to use on the road/pavement?
• I have seen some electrically assisted pedal cycles advertised are they legal to use on the roads without insurance etc?
• I've heard that it's lawful to use electric scooters (e-scooters) on the road, is this correct?
• Kids are driving up and down the road in cars and I don't think they are old enough to drive, can the police help?
• Local youths are riding up and down the street on go-peds / motorised scooters / mini-motos. Can the police do anything?
• There are always youths on bikes/ in cars screeching up and down the road, it is very dangerous, what can the police do?
• There are kids on quad bikes/motorcycles riding up and down the field near to where I live and it is very annoying - what can the police do?
• There are kids riding go-peds / motorised scooters / mini motos on the pavement causing danger to pedestrians, what can the police do?
• What driving licence do I need to ride a Piaggio MP3?