The steam appliciation is free of charge. Whatever games you want to play through it, you obviously have to pay for. If you order now, you get a 10% discount (it’s now at €35.99 instead of €39.99). The game is already available for preload (i.e. you can download most of the game now, and a small portion on release so you can jump in immediately. I’m not sure, but it might even be possible to have it earlier in Europe if you establish some sort of VPN connection through the United States).