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Only material that should be used in brake lines is steel. I've seen brass ones recently) and your intermediate fittings, reducers, adapters etc. are usually brass.
In respect to this, can you use brass compression fittings on brake lines?
Because of the unreliability of compression fittings on brake lines, the use of compression fittings is not widely recommended. If you are repairing the brake lines in a vehicle that is not a passenger car used for everyday road travel and transportation, compression fittings are an acceptable brake line repair.
In respect to this, can brake lines be spliced?
Contrary to popular belief it is NOT illegal to make a new section of brake line and splice it into a non-rusted section of your old brake, as long as you use automotive grade SAE double/inverted flare, SAE “bubble” flare and DIN Single Mushroom flare unions and fittings.
As for the regular copper tubing used for brake lines, sure, it's better than a rust-perforated steel line. But if you're going to trust your brakes to stop you from high speeds or in the mountains (unlikely in Newfoundland) then it had better be more than straight copper.