A bad ground will definitely keep you from starting. For instance, if your ignition box isn't properly grounded to the body of the car. In answer to your first question, a bad ground will not hurt your ballast resistor. If you have an ohm meter, you can disconnect the wire off one end of it and measure the resistance across it. If you have a 2 connection resistor, it should measure no more than 1.2 ohms. I'm not sure about the 4 connection resistor...
