Good question! I dunno the answer, but I know some of it!
When I returned to Australia, I discovered they were invented and developed by an Australian, and there's a book out there all about it (which I've not read!). Firstly they don't always survive, but are built tough to survive most likely scenarios, I'm not sure if making them orange has a positive effect on their chances of survival, but it helps in getting them found.
They are nicknamed called 'black boxes' because their contents are a mystery, (black = covert) rather than they were ever that colour. The proper name is flight data recorder, and IIRC they're basically a development of the W.W.II era wire recorders, which are a tougher version of tape records we pre-digital age guys will understand. For the kiddies, "it's all done by magic".
And for some more, more likely data:
http://en.wikipedia.org/wiki/Flight_recorderhttp://en.wikipedia.org/wiki/List_of_un ... _recordersAnd for the question of why they don't make aeroplanes out of black box stuff - the other answer is because people are squishy and vulnerable to the wrong amounts of stuff like oxygen and water.