Hi and welcome to SIDC!
I have a new euro import, the price of 21k will not include a tracker or alarm, these will cost you another 1k approx. The euro import will not have the 6 airbags, only 2, but this means you get better seats [] You may have problems getting your service book/warranty sorted out, but just keep chasing whoever you buy the car from and all will be good.
The only "downfall" of buying an STi is the fuel, but the smile factor more than makes up for that []
Hope this helps and good luck!