The question cannot easily be answered until #6 is fixed.

If the engine starts after one full glow cycle and doesn't kick and bang in the process, you can continue to use your old plugs.

However, like my '86, the old plugs don't put out the heat of a new plug and it's absolutely necessary to wait 30 seconds from the point of turning the key until you crank the engine. Just ignore that glow plug light...........it's useless unless the temperature is above 70°F. or the plugs are brand new.

There really is no reason to cycle the plugs twice. You'll likely get sufficient heat to start after 30 seconds............whether it will be a smooth start is the question.