Conversation Between bonesetter and Fatharrydog

Hi I am thinking of buying a WRX Type R V4 V-limited. I was given your name in my original post as someone who knows about these cars. Is there a big difference with the STi? Do they share the same engine? Can the car be mapped without having to replace the ECU? Is there a big difference in desirability and resale value compared to the STi? I am hoping to get it for around £3750 and it is in reasonable condition (imported in 2010). It is on Gumtree for £4200 if you want to have a look. Can the brakes be upgraded whilst still retaining the ABS? Many thanks in advance for your help. Regards, Steve