Dont waste your time putting 12 pot or whatever calipers, put something that works right for the weight and power of the car, a good set of 6pot fronts and 4 pot rears would work just fine. Just make sure the application is for what you will be using the car for!
For the ECU, use which ever one your Tuner has done the most work on, unless you plan on bringing in a specialist to tune the car over there.
Personally i like the HKS unit, biggest negative aspect of that is that very few people have the software to tune it. So going for a more open option is always better.
If you are going to run GT ball bearing turbos, i wouldnt bother running any blow off at all
one less thing to bother about. But choice is yours and depends if you feel you need them of not.
Has Cyprus relaxed on their modification laws or something lol! Ah memories of cops running out of road side gutters hailing me down for speeding at 3am going up to Troodos ROFL!