I have indeed heard of Kazimerez....a labyrinth of bars and Jewish architecture ?
Yep, it's a laid back area with some great little haunts to explore. You will have fun I am sure :)
what is the going rate these days for an hour of English with a native english speaker?
Depends really on your reputation and what the students needs are. The longer you have been teaching there (and hopefully not rearranging your lessons due to heavy hangovers...or even worse by being outright drunk) the more you can charge. For starting off, a nice bet is 40z's an hour. Once you have been there for a few months you can start asking for more. Also depends on your client. Because of the amount of teachers there, its a good idea to have them tied down after a couple of lessons, if you think they can afford it, ask for a month in advance. Krakow's students tend to be a little unreliable, so don't sell yourself cheap.
Will you be looking for work at a school?