Not heard of the resistor built into the coil, would have to see the skematic of the coil to see whats going on inside.
If you get a plain old standard 12V coil, yes, again it will make your points last longer. When car and tractor companies switched to 12v all ignitions had ignition resistors. GM started solenoids had a pole that provided 12V that was wired to the coil side of the resistor. Ford ran a wife from the starter solenoid pole of the ignition switch for the same purpose.
You don't have to, just keeps the points contacts cleaner longer.
Mike
