The conference hotel is a little outside of Kraków and there are not too many other options around. Unfortunately the hotel is booked out please use one of the many booking sites to find a place to sleep.
Travelling in Europe is relatively easy particularly if the country is part of the Schengen Area, which Poland is. Within this area you will not find borders between countries and people can move from one country to another easily.
The problem for some people is entering the Schengen Area and depending on your Nationality the process and the documents you require are different.
Kraków is a very nice city with a lot of options for things you can do before or after the confernence. Here are some tips: TRAVEL GUIDE & TOP 10 FREE THINGS TO DO IN KRAKOW, POLAND