For the most part, the shape of the sign is for only one thing.
And that one thing is so you can recognize what type of sign it is at a further distance away (a diamond warning sign, you will know to slow down before you read what the warning is.)
True
Yes
that one sign, with that one shape to it... you know that tells you to do those one things
A stop sign is in the shape of an octagon.
A stop sign is octagonal in shape.
WHAT icons? If you are referring to the SHAPE of the signs themselves, the shape of the sign itself signifies the type of information the sign conveys. (e.g.: Octagaonal signs are ALWAYS stop signs - Diamond-shape signs ALWAYS convey some type of warning message - etc).
It is in the shape of a shield.
A Fermata
A regulation sign is a sign that gives you the regulation for something. These signs are always in white and black and rectangle in shape. An example is a speed limit sign.
Its a Stop sign
Vertical triangular shape.
No. It is already indicated that it is positive without the positive sign on the number.