I was traveling in Germany recently, and asked my german friend basically the same question. From what I could gather of his explanation, it seemed like 'line' might be a useful way to translate 'Bahn.' As in, 'I took the green line to the blue line and then got off at the airport"
This, (at least to me) explained why you'd have things like the "Autobahn" (car-line), "Untergrundbahn/U-Bahn" (underground line), Bahnhof (line-yard) and other such things.
Not sure if that's proper, but it helped me! :)
fahren means to drive. But there are instances where it would sound weird to use "drive", while it is perfectly fine in German to use "fahren", so you will need a different verb to make it okay in English, too:
Deutsch: Ich fahre in Urlaub - literally: I drive to vacation - proper English: I go on vacation
On the contrary. "Fahren" is a general term that covers pretty much any form of travel that doesn't involve using your own power (walking, running, ...) There is no English equivalent - "to drive" is too narrow, "to go" is far too wide. Therefore DL uses the closest which happens to be "to drive". When I say "Ich fahre mit einem Bus." it means I travel by the bus. It doesn't imply I am driving it (that would be the verb "lenken")