one car length for each 10mph
You should probably not be following one in the first place.
No generalized answer can be given. This can be different in every state.
Maintain a safe distance between vehicles. Never tailgate.
The distance one must maintain behind an emergency vehicle actively engaged in a response, or a pursuit, will vary by state regulations, and even sometimes by local jurisdiction. Fire apparatus customarily has this distance stenciled on the back of the equipment. If it is a law enforcement or emergency medical vehicle you must be aware of your own jurisdictions regulations.Note: Unless you are also operating an emergency vehicle, you may NOT follow one engaged as above. It is against the law to do so in every jurisdiction I am aware of.
What is following distance? Following distance is the space between your vehicle and the vehicle in front of you while driving. It's important for all drivers to maintain a safe following distance, so that they have time to safely stop in case the vehicle in front of them brakes abruptly.
They are not classified as a vehicle at all. They have no motor so are classified in the trailer group.
Grant the emergency vehicle the right of way.
A safe distance, there is no defined limits of this type as driving near parked cars is situational (at best).
Both A & B
No
Yes if you are just following it to see where it is going. It is however not illegal to be going in the same direction as an emergency vehicle as long as you stay 500 feet back. If the emergency vehicle is not using its emergency lights or sirens, and is not stopped at an emergency scene, you can treat it like a regular vehicle and follow it as would be legal for any other vehicle.
A wrecker is considered to be an emergency vehicle when it's emergency lights are flashing. Under normal circumstances a wreckers lights are not flashing it is just a truck or service vehicle.