For the 312s I believe you need callipers, carriers, discs and pads, but I'm not overly sure.
The engines seem awesomely strong, even after the mileage mine has done its never missed a beat - as long as you keep it serviced and well maintained I don't see why they wont be good for 200k+
The strut brace has made a slight noticeable difference, but I'd have to take it off now to tell you how the car drives with/without it as its been on for ages. i mainly wanted it to add some colour to the engine bay!
Best way to tell if your car has been mapped it to get it RR'ed and see what power it produces - mine was producing 138bhp standard, and 175bhp mapped.