In some states, an off duty police officer can write a speeding ticket. It will depend on the laws in your specific state. You can always go to court to fight the ticket.
Yes, an off duty police officer can write a ticket on or off duty. The ticket can be mailed to you, or you can be served with a subpoena to appear in court to answer to the charge on the ticket.
Yes, although the practice is generally discouraged. Police officers retain their police powers 24 hours a day, while on duty or off.
"Police" usually refers to a body of people, so the term is usually plural. "Were" is correct, e.g. "The police were present at the scene of the crime."
Of course! The may be off duty but they can still arrest you.
Police car, or Police Department.
Is it legal? If the off duty police officer has commited some sort of ticketable offense, yes.
Police presence is simply an aura of the consistent presence of police in a particular area. It can also be the effect of increased police patrols in an area. Someone might write: "The increased presence of police in the neighborhood resulted in a dramatic drop in crime."
If you are a police officer you would not need to ask. A police officer doing his duty will treat another police officer as any member of the public (if they are out of uniform and off duty).
if the call of duty requires it, yes police can speed.