Don't think it will pay to do that in a provincial town, you need tourist to make it work, unfortunately not too many tourist visit that part.
Somebody has to do it at some point, and these kind of people are the ones to take a risk and make the money. I would imagine that Rzeszow has arouund 180,000 + inhabitants. That should be enough to carve out a profitable business for the right bar with good quality food.
Keep in mind poles do not eat out, they prefer to cook there own.
Thats not really true, Poles love to eat out, most just cant afford it.
In reply to the original question regarding price its a mixed bag. The links above from Nierozumium look about right as for rentals anything from 35pln / m2 / month. Look out for scams though. Consult a lawyer before signing anyhting.