Well, sort of late. Will be landing at Okecie at 22:30. Which means that to get into town will probably be possible only by taxi. Am I correct? To avoid the con taxi drivers, would I need to phone for a taxi or can one rely on the regular taxi stands?

Use the telephone! Smile at taxi touts and shake head. Alternate, either the Airporter bus or the city bus...Schedules are posted at pickup points. Use ATM to get zlotych.
Marriott also has bus service. Your hotel may have limo service.

PolskiExpress busses will take you to Center ("Centralny" Train Station), also regular city Bus still will be available - although around that time I would not recommand to "land" around "Centralny" or take City transportation. Best is to take a taxi. check this site for one that have been around for years and has good prices as well as service.
http://www.mpt.com.pl/taxi_eng.htm

BTW ... as GSteed recommanded - do not use any "taxi drivers" that will try to "pick you up" at arrivals... those drivers will rip you off...

Use http://www.mpt.com.pl/taxi_eng.htm
ask them to pick you up at some spot at the airport with your name printed on paper - so you know that this is the right person.(they do this all the time) also MPT Taxi has a booth at the airport (but at that time they maybe closed - so use the website to order a pickup)

PeterB: Bardzo dziekuje! That's an awesome site for taxis.

Eli: Prosze Bardzo! Przyjemnych wakacji!