1. If we want to rent a small flat, how much shall i pay for one month?
More or less 1200PLN but It will be hard to find something only for one month.
a barrel of mineral water(4L) costs about 1.14 US dollar which equals 0.74 EUR. What about that in Poland?
Good water cost here $1-1.5 for 1.5L, you may find in Tesco or something 5L for $1.5-2 but that's not much better than tap water...
What do poles eat usually?
Meat, potatoes etc...