If my memory serves me correctly, standard suspensions whether it be from a dealership or or everyday parts shop are usually black, so sports suspensions tended to be coloured so as to be shown off in the arches. I had sports suspension fitted to my old mini which were the GAZ shocks and these were bright yellow with the gold adjustable knob for hardening the ride of the car (as if it wasn't a hard ride without them anyway).
Bolster seats- I always thought this varied depending on manufacturer the companies i have worked for in the past bolster seats tended to be half fabric half leather but it also depended on the spec level of the car too, but i could be wrong
As for the wheels, its does say centres so maybe they decided to paint them up to match the wheel or they had to be painted before the car was sent out.
I aint sure how correct i am on the last 2 but i am pretty certain with the shocks.
(watch this someone will tell me i am wrong)
Sarah