don't want to sound like i'm teaching you to suck eggs but the brake lines haven't a thread on them you have to slide the connection onto the end then swage the end of the pip to create a compression seal.
no to ally as they are too soft and corrode.
stainless steel sounds great but they are very hard to flare the ends with a low cost flaring tool.
buy the std copper nickle tubing as its easy to bend and flare plus it oxidises over time and creates a corrosion barrier.
pure copper lines will corrode through after time.
if you want to get fancy buy some heat shrink and slide it over the tubing and warm it up, some various colours as well