Speaker wiring

[Checkmate1990]

Hi all
My names Ed I’m new on here I have a 1990 998cc checkmate and when I bought it there was a bunch of wires hanging down onthe passenger side so I got curious and followed them and found that the last owner had some sort of sound system in the car and I would like to put it back in but I need some pointers .
There are three thing I would like help understanding
1 there is a green wire that has a inline fuse then goes to a box then out somewhere I don’t know where. I have a feeling due to the fuse it’s the power but I need some one to confirm this

2 what speaker connects to this wire
These wires go the whole length of the car to the parcel shelf whether a pre-drilled holes I wanted to know what speaker fittings would fit onto these wires As I have never seen them before.


3 the 4 wires
There are 4 wires 2 black and 2 black and white that go to the end connectors this may seem stupid but are these the wires that I connect to the back of some sort of radio for the speakers (wiring is not my thing)

Any help at all would be appreciated thanks