I am an American citizen and my fiance is Polish. We are getting married in poland in September.
Don't do that. :)
She can apply for K-1 visa in US embassy in Poland as your fiance.
She can enter US on K-1 visa . You have to get married in 90 days after her enter.
After marriage you can apply for green card for her and advance parole document, so she can travel abroad.
She will receive an employment authorization card in 3 month and green card in about 1 year.
Don't apply for tourist visa, because she in not eligible for tourist visa if you plan to get married.
You can do unofficial marriage ceremony in Poland after that.
use google and find more information about K-1 visa, advance parole document and adjustment of status. I-131, I-485, G-325, I-765
You don't need a lawyer to fill out all documents. It is not difficult, but you need to spend some time googling and calling DHS. Tell her to take her birth certification and sworn translation of it. All (also expired) passports will be needed.