I've been offered a job teaching English in a medium sized town (c 100,000), in central Poland.
Could you be more specific? A lot depends on the place.
The salary is 2000 per month. Gross, I think.
Have they mentioned what kind of contract they'll be employing you under? Taxation could range from 9.5% all the way through to nearly 40% - so you need to be careful.
I've also been offered an apartment shared with another Teacher, free of charge. The school also pays the utility bills in full.
Don't do it. It's asking for trouble - Polish employers will *always* put the bottom line before their teachers - and if it means throwing you out of the flat (and trust me, it will be a flat, not an apartment) in the middle of winter, they won't care less. It's pretty much universally accepted in Poland that accommodation from an employer usually leads to trouble.
1/ Is the salary sufficient to live as I've described?
Find out if it's net or gross, and what "umowa" you'll be employed under. I'm 99% certain they'll be paying you under the so-called "umowa o dzielo" - which means a tax rate of either 9.5% or 18%. However - one catch - you won't have public health insurance paid-for under this system.
2/ Polish culture: Is the salary offered with a job often negotiable? Would it cause any offense or bad feelings to go back to the employer, and try to negotiate a higher figure?
Often very negotiable, but given the deal, there's probably not much room to negotiate.
How many hours a week do they expect you to teach?