I apologize if I post redundant information - I don't have time to browse through previous pages. You may find my own experience useful.
1. As for a handgun - technically, if you have a permit in Poland, the law does not distinguish between concealed or not. The social expectation would be that you actually carry concealed.
Getting the permit, however, is next to impossible. Poland's laws are extremely prohibitive, compared to the rest of Europe. You need to provide a compelling reason (e.g. receiving threats).
2. There is a loophole with respect to long guns though. If you have a hunting license in the U.S., you can apply for a membership in the Polski Związek £owiecki, without the normally required 1 year training period - foreign hunter licenses, per PZ£ regulations, waive this requirement. You just need to take a hunter education class (a few months), pass an exam, and you will be free to bring your long guns to Poland. This is costly, compared to hunting in the U.S., but at least doable.
3. The process is NOT friendly, in any case. Actually, a couple of years ago I tried to return to Poland after some 8 years in the U.S. All the problems with bringing my guns to Poland constituted about 30% of the reasons why I gave up and moved back to the U.S.