The brake master cylinders dont go on all cars its just an issue that has happened to quite a few ,just test the brakes well to make sure they are not to spongey and work well and also the cylinder starts to make a noise when it is starting to go, if you do as search on here you find out exactly what to look for and what to listen out for.
Also check for steering wheel wobble cars are prone to that , get the car up to a good speed and see if the steering wheel wobbles at all.
When comes to checking whether the car is young or old its the same with all cars, check steering wheel to make sure its not to shiny and worn , check all the pedals to make sure the rubber on them is how it should ie if all the pedals rubber covers are worn away car has done lots of miles, check seats to see how worn they are can idicate the mileage just check all the interior well, again it will show how genuine the car is.
When test driving at low speeds brings the windows down so you can listen out for any unusual noises and check all the equipment to make sure it works ,press every button.
Obviously with the mileage it has done it will have natural wear and tear but that has to be within reason,
Hope this helps theres lots more i could write but have to go just be sensible and dont let your heart rule your head if anything is not right about it walk away .
James