What are the advantages of serving fries in a metal cone?
In a traditional British chip shop, you would have got your chips (fries for Americans) in yesterday's newspaper, wrapped into a cone shape. These days of course, it's food grade greaseproof paper, but it's still in the same shape.

I suspect the reason for serving chips in a cone is that simple tradition. Also, there may be thermal reasons, that it allows the chips on the top to get cool enough to eat, without the chips at the bottom getting too cold by the time you get to them.

I can't speak about the seasonings. Traditional chips would just have salt and vinegar poured n from the top by the customer himself.