Hmmm, very interesting questions. I'm in exactly the same boat. (but on a slightly different seat from you)
lol
I have a factory fitted CD Changer, same as you. I have just recieved my MDI (brand new for £38!)
so am keen to find out if I need a new loom or can I use my old loom. I've already upgraded to a RCD510 and noticed there's no seperate loom for the CD Changer.
I already have the wee short ipod lead but wud prob like to use an ipod lead so I can use my phone whilst driving (sat-nav) or so that others in the back can change tunes, etc.
Any helpful info will be mucho appreciated.