Yes MKIII's make good first cars, but never a turbo with 400 hp. No turbo car, especially one with 400 hp makes a good first car.
You need a non turbo, hopefully automatic for a first car, then you can learn to swap parts and EARN your horsepower. This car can spin tires and spin out (ask me how I know), even stock and beaten to death with over a quarter million miles. Even after having my 89 for 5 years, and having it turbo for the past 3, I'm still not 100% confident in driving her hard because I have no idea when the rear end may come loose, even though I just swapped in a TT-R differential..
You are probably very young and inexperienced. Trust me on this.