I can tell you about Warsaw.
1euro=4.2 PLN (polish złoty)
Renting the apartment is still ahead of me so I won't tell you precise price, f.ex. i found some site for renting in Warsaw
http://erasmusinpoland.com/eng/offers/index
The food is quite cheap comparing to Italy i think. A dinner will cost you around 14-25 złoty. Exemplary prices: small subway sandwich ~10zł, big mac menu 16zł, meal in chinese restaurant 15zł.
I will provide you some more info in the evening because now i must go to the university
Is there something you want to know in particular?
In the meantime maybe other polish members will tell you sth @radekas @jakku7