A great list!
I have a couple more to add, apologies if they've already been covered by other posters.
1. Front footwell carpet removals
I think this happened in early 2003 (I've owned two '52 plate 75s that have had the carpet, but I have yet to see an '03 plate that has the carpet in the footwells.
With carpet
Without carpet
2. Rear of the front seats (Classic and Club only)
My last 2002 Rover 75 had a plastic facing to the rear of the front seats, whilst 2001 Rover 75 has velour.
With velour
Without velour
The plastic in the footwell is a particular bugbear of mine. And once you've seen it, you can't unsee it.
Cheers,
Andrew