4 red flags
Rule stop marker and tail on a light bar attached to rear most part of load and also side markers on bar. I have gotten away with a 3 light cluster but you take chance this way of a citation.
they are suppose to be red and you should (to be safe) have 2 one on each side.
Cargo
This answer is DIRECTLY from the Florida Drivers Handbook:In the day time,4 red flags at least 12 inches square must be placed on the projecting load where red lamps are used at night (extreme rear and sides)NOTE: if the trailer or motor vehicle is transporting logs, long pulpwood, poles or posts that extend more than 4 feet beyond the rear of the load, then you must have one amber strobe-type lamp equipped, so that the lamp is visible from the rear and both sides of the projecting load. The lamp must be operational and seen any time of day or night.>I hope this information was great use to you...GOOD LUCK on your exam! =D
The double mark after the 6 indicates inches. If it was a single mark (') - that would mean feet.
It is known as the plimsoll line, originally called the plimsoll mark.
By mark for feet I assume you mean equivalent of cm or some such. If you were to describe my height in feet and inches I would be 6'4" This means I am 6 foot 4 inches.
There are many variables including vehicle type, road composition, etc. The following examples are for dry asphalt, passenger car, dry road, no antilock brakes. 30 mph is 40 feet, 40 mph is 71 feet, 50 mph is 111 feet, and 60 mph is 160 feet.
It depends on the dealer and vehicle. Usually the mark ups the dealer add on like special mats, wheels, accessories and market mark up etc...
mark it with door number
If you mean this in car/vehicle terms then I'm sure its the registration plate.....Vehicle Registration Mark