PM, thanks for your erudition and on the mark, as always. Asc far as havdalah on yom tov goes, I always remember in my father’s z’l house, we just made the brocho without putting the candles together, and looking at the candles after the brocho,as you write. I don’t remember whether we looked at our nails- I think not.
You may also know that , if my memory serves me right, by certain Sefardim, they use only one candle, and not two or more, as we do.