Now as far as marrying on a tourist visa, you can legally do it, but she will have to return to Poland before her tourist visa expires, and then you will have to apply for a spouse visa.
Not true.All she has to do is to apply for "adjustment of status".I think it cost $1070 (including biometrics) but check on USCIS page.
She cannot stay in the US to receive a spouse visa while being on a tourists visa, even if you get married, because a tourist visa is just that, for visiting and then going back to their home country.
Utter BS.Once married (in the US) she DOES NOT need any fiance visa.