Students and staff want to speak English, who else is there? People in the street?
You live at your job? How do you get through the rest of your life in Poland?
Altho once one has come for 'just nine month' then come back to do 'just one more academic year' and then 'this really is the last academic year and then I'm off' and spent three years in Poland not speaking the language, that teacher has probably got used to not speaking the language and so doesn't see the need to bother.
This sounds more like a British thing (IME Americans have a much better track record with learning Polish than do Brits). I think it comes from different expectations about social lives, Brits seem to do okay knowing just three people while Americans like to know lots of people (for which you generally need Polish in Poland).
Depends on how much one works and how much one prepares. Perhaps you don't do enough of one, the other or both.
Depnds on how much you need to work and prepare. The teachers I've known with the heaviest work loads did speak Polish.
Whats important is that they can inspire / assist their students in learning the language themselves, not their own ability with L2
Do as I say, not as I do?