You can OLCI for AMS-WAW 30 hours before your flight (and get a seat before those poor people who posted here that it is 24hrs).

There is no such thing as Europe Select any more. Europe Business class however does exist, as well as Economy Comfort seats or Extra legroom seats (exit row for the 737 you will be on). As stated before, FB Plats only get upgraded when oversold in the back, so your chances are somewhat greater than a Plank's constant.