First of all, are you polish citizen too? If not, you will need polish "green card". And it is not so easy to obtain.
Gdansk is really a nice city. Actually I mean tri-city----Gdansk,Gdynia and Sopot. Especailly Sopot. You are gonna to love there. Well, I am not a Polish. Only lived there for one year. I really enjoyed there in Tri-city. People are friendly(most of them) and really quiet place (for me:P). The last summer was great:) good luck and enjoy:)