Stodala is working and You can finad in the main hall, on the right side a guy (usually with his daughter) selling filns, papers and dev. They are afv.pl, so You can can make a choice on the net and get it in the weekend. Another guy is on the right side just after You enter.
BW in cold process You can bet in Czarno Białe or at ProfiLab (main office ul. Dzika). Mentioned Foto Relax at the back of empik is not developing in cold process any more, but c41 or scanning/prints You can get for sure.