1)No
2)Reference # 1 above.
3)Measure the diameter of the wire, not the insulation.
4)
http://en.wikipedia.org/wiki/American_wire_gauge
There are many factors that go into choosing your wires. The first thing to look at is how much current or amps the wire is likely to endure. ie: the wire/cable going to the starter must be a very heavy gauge wire to handle the large current drain needed to operate the starter while the wire needed to power the overhead lamp would be quite small in comparison.
Other than the current handling capacity of a wire you need to look at where the wire is going to be used, under the hood/bonnet or under the dash. If the wire is going to survive the environment under the hood it must be able to withstand heat, water, ice, abrasion, oil antifreeze, grease and road kill (free cat?).
Under the dash is not as demanding but why skimp?
When replacing wiring it is mandatory to use at least the same gauge wire as you are replacing, it would be nice to use the same color as what you will be replacing but that will get very expensive buying a roll of wire for each color and you will have a lot of wire left over. Mark the wires you replace on each end to help yourself and the guy/girl who gets the car next.
I'm sure someone sells a complete wiring harness for your car, again probably expensive.
Replace what you have to and secure it well away from heat sources and other moving parts, groument holes where wires pass and cut wire ties close, very close they can and will cause leaking of the red stuff from your arms and head not to mention the slippery words that come out of your pie hole just before the leak is detected[B)].
Maintained on Saturday…Drive on Fun-Day !!! 1976 FHC - 1980 DHC