1) Impossible to say without knowing why it's a non-runner. The clicking ECU could be something minor (battery problem). But the rock bottom price you paid for this car would suggest there is something much more serious going on with this car.
2) As per 1), it's impossible to say. You could easily spend another £4,000 on a replacement engine.
3) I'd recommend using our Good Garage Guide: good-garage-guide.honestjohn.co.uk/north-west/grea...r