Blades
Start by knowing that I know nothing much about notation.
But if you are in the key of g where c would be natural, wouldn't you just display c anyway (without a natural symbol) ? I guess I understand why within a measure that had an accidental followed by the natural form you would show the symbols for both, but I thought you only generally displayed a symbol at all when it was an exception to the key.
When something is sharpened, it stays sharpened for the rest of the bar. In other words, you show the sharp for the first occurrence, then every other occurrence of that note in the bar is assumed to be sharpened until you use a natural sign.