oki doki,the way your old head unit was earthed was just dodgy and lazy.it should have been earthed to a decent bolt or screw arount that area,theres one just under the rubber gear shifter boot that you can use.
from the look of the plug on the back of the new unit you have it apears to be a sony so you will need to get yourself some of these
http://www.aerpro.com.au/list.php?pcode=AP...=10&cat_sno=
that one is to suit the cars plugs
http://www.aerpro.com.au/list.php?pcode=AP...=10&cat_sno=
and that one to suit your CD player,they will interconect in the middle so you you end up with one lead that goes from your car to the CD player.i beleve some people have had issues with the plugs not working because the earth in the new plugs was not correct.so you will have to cud the earth wire off the car side of the plugs and put an eyelet terminal on it and earth it to a decent place (as i mentioned before).
the big black plug in your seccond to last picture is your antenna plug. i dont know what the grey one is,possibly the trigger wire for the booster that goes with the antenna in your front windscreen.if you plug it all in and you find you get really poor radio reception then that is more then likly what it is and you will need to hook the P CONT or ANT CONT wire up to it. if your radio only has the ANT CONT that is fine.
the big black plug in your last picture apears to have been taped into the power for the cigy lighter so is obveiously not factory and you can just leave it be.
The Aerpro plugs are available from autobarn,strathfeilds etc etc,if they dont have them off the shelf they can be orderd in for you,they will cost you between $14.99 and $20 each.
hope that sorts you out mate!
Jack