I have bought a cassette player and want to replace the CD player with it. Do I need to take off the whole centre console? Also when trying to unscrew the passenger parcel shelf the screw moves but doesn't come out.
No. You "should" be able to take the surround off the front of the cd player and then put a radio key down either side of it. Then it will just slide out. Different radios use different keys but most of the time if it's an aftermarket head unit you can just use 2 long thin screwdrivers or two thin flat bits of metal.
Look on the sticker on the radio, it shows you which wires you need. Red is live, black is earth, the blue one is for an electric aerial and the two plugs are speakers. Take a picture of what you've pulled out and I will tell you what's what.