The carbon fiber roof may still be coming to be available as an option but still has not been spotted in testing. Expect the Golf R to basically share similarities with the Audi S3 which means a 2.0 turbo direct injected four-cylinder (likely slightly detuned for the Golf R) and all wheel drive with a dual clutch transmission option.
From the video the engine note sure could use some work as the car lacks any aural punch. Nothing an aftermarket exhaust won't cure but still one would expect a bit more bark. Expect this car to be revealed any day now, it's time.