The SMG was available for euro M3's a while back, But I hear not many people liked it.
and yes that button behind the shifter adjusts how quickly/smoothly the car shifts. It also adjusts what gear the car will be in in automatic mode. The lower the setting, the smoother the ride, the higher the setting, the faster and more forocious the car will respond.
and my next mod will be exhaust. My buddy just got Borla on his WRX and I nearly peed myself the first time it fired up.