430 Scuderia - clutch and brakes measure

Hi everyone. I am from Switzerland and new to this forum. Absolutely great site, lot of information, polite conversations, etc.
I am actively looking to buy a Scud - crazy market at the moment - no cars are selling and sellers are not keen to reduce prices - anyway that is another discussion....
I have seen some great posts here about around what to look for, etc, so don't want to repeat that. My questions are basically the following:

1) what is a reasonable clutch, brake pads, discs wear percentage for a car around 20.000km (12.500miles)? E.G. currently one car has 85%, 50% and 90% respectively - is that in line with a normal driving?
2) at what percentage do ALL these parts need changing usually? e.g. are the pads useless when they are at 30% or can one drive until really approaching single digit percentages? E.G. On non CC brakes when pads are below 30% the heat transfer to callipers is preventing optimal braking when driving properly.
3) is there anything significant that Ferrari powere guarantee is not covering in your view?
4) is buying a car that has done virtually zero miles within first five years, and then 10k miles until now a bad idea?

Many thanks in advance!
Carlito