im sure I've just read on someones work log that they've created the interupter for the reverse/camera thing.
with regards to signals, if im not mistaken you need 2 points of reference to locate the position of a signal. You could however work out the direction, but again you'd need multiple receivers positioned to work out the angle of the signal. I may be wrong however
also, why would you like a cd changer linked to your pc? why not just rip all your cds to mp3??