Resistor wire - what's it for?

[[JP]]

What's it for? does anyone know? I've read about this ignition resistor wire, but not sure why its a resistor wire and if really required.

So, my 65 Chevy C10 has a 350 Buick engine in it.
The wiring was a mess as some of you know, I've redone the wiring.

The wire from the ignition to the coil was not a resistor wire, when i redone it I used 28/0.30, not resistor wire either.
All good, truck starts and runs like it used to before I ripped the wiring out.

Found there's a problem on the coil- if you tighten a nut too much then it wont work, so I bought a new coil.
this thing here:


now on the instructions it says I have to use a ballast resistor. which is fine as the coil came with that resistor:


but then I found this diagram online..



this diagram again mentions the resistor wire.... what is it for?
and another question... I dont have a wire going from the coil to the starter motor - why is this wire there? is it necessary?
All I have, in relation to starter motor (and was like this when I got the truck) is a wire from battery to starter motor, one from ignition straight to starter motor and that's it. truck starts and runs though.. so i'm also curious to know what is the wire to the coil for?
the original wiring diagram does show the wire going from ignition to starter and then coil, but on mine is going straight to the coil




So basically after all the babbling there is 2 questions:
what's the resistor wire for
and whats the wire from coil to starter motor for.