fuel line

Not sure about how copper would react to todays fuels. Looks pretty, but I wouldn't use it. Aluminum is fine on a street car, but I have seen it crack. Give yourself room for expansion/contraction and take flex points into account, you'll be fine.

Double flaring for automotive inverted flare fittings is needed with standard galvanized steel line. It has a sean that will split if you don't. I don't recommend using this line with AN fittings, although I have done it and seen it done. I prefer using stainless with AN stuff. Also, AN fittings are single 37 degree flares, as opposed to SAE inverted flares, which are 45 degrees and can be single or double depending on material.