Just to add that I also need to know what speaker wires are available and where do they start, where do they end and how do they get there (approx.)?

It is likely that there's a link somewhere to a wiring diagram that apparently shows this, but I am hoping to avoid spending the inevitably huge amount of time trying to fathom it out, especially when it finally proves to be unrepresentative of my ampless UK spec car. I'm sure someone must know the quick answer to my questions, off the top of their head, so I am asking for your help - please:-)