Unfortunately I can't answer most of the queries you have, but in addition to the pieces you mention as being needed, you will also require a sat nav aerial, and a different dash trim piece to cater for the much larger screen fitted. I am not sure if the interior of the glove compartment trim would also be a different shape to cater for the disc reader.
You could check to see if you have a sat nav aerial pre-fitted by locating the junction box on the rear offside pillar where the radio aerial and sat nav aerial are plugged in, having been routed down from the roof. Cables then disappear down into the car to emerge under the back seat at the amplifier, and in the glove box for the disc reader.
A further thing to consider is that the system cannot be updated with discs beyond 2015, which is the last update that will be made available, so you may be better off fitting a more modern system somewhere unobtrusively, that is capable of receiving updates.
I am grateful for the system in my car but it is a rather old fashioned one, and certainly not as easy to use as a modern Tom Tom or similar.