I'm Polish and feel the need to clarify ;)
First, it's quite a bad idea to translate English (or any other language, actually) to Polish. Polish has complicated grammar and automatical translators often come up with completely unreadable gibberish (although I guess you have to do it when you have no other choice). Polish to English, however, works well enough.
(the latter part of this post contains bad words, so if you're gonna be offended, stop reading)
Some Poles do curse quite a lot, I noticed it too, although I have no idea why :P. On the other hand, I've seen a good amount of "fuckers" and "bitches" thrown around in English as well. Certainly, it's not language-dependent, I even feel that English "allows" swear words more.
"Kurwa" basically do means "whore" (as Google Translate translates it), but it's mainly used as an universal swear word, like "fuck" or "shit" in English. It can also be used to describe someone who you would call an "asshole" or a "fucker" - we don't have many swear words, but they are all really flexible ;) For further reading, I recommend http://www.polishforums.com/general-language-17/polish-swear-words-139/