The average exchange rate between Polish currency (złoty, also denoted by PLN) and dollar and euro range 1$ ~ 2.8 - 3.2 PLN, 1 € ~ 3.7 - 4.0 PLN. An updated exchange rate can be found on the web page of Polish National Bank . In Poland you should pay in Polish currency or by credit card. In very few places you can pay in euro. You can exchange main currencies (US $, euro) at exchange points (called kantor, in Polish) or get cash at ATM machines. The exchange rate at kantor in the airport or train station is very bad, up to 20% lower than the average.
There is no conference fee. Your expenses during the stay in Warsaw are for lodging, meals and local transportation.
Lodging: The Banach Center reserved rooms in few hotels, the price will be in the range 150 - 200 PLN/night, which is approximately $50 - 70/night or 40 - 55 €/night.
Meals: The cost of meals will be approximately $20 - 40/day, but, of course, the upper limit will depend mainly on you.
Local transportation: It is described in when you arrive section.