I'm sorry for multiple quotes, but there are some separate things that need to be addressed here.
DominicB, grow up please and leave the adult work to the intellectual layer of society.
OK - first lessons for you - Poland is no place for self-proclaimed intellectuals. If you use that kind of attitude here, you'll soon run into a very big brick wall.
Further Kozminski is #18 master in Finance & Accounting in Europe with a lower tuition fee (8.500 zl), higher positioned than Vlerick in Belgium
Where did you get that from? Kozminski doesn't even have university rights in Poland. It might be called "Kozminski University" in English, but "university" isn't a protected title, unlike "uniwersytet". Furthermore, unless you already have connections in Poland, the degree itself won't be worth much.
1) Because the university is higher ranked, the best quality institute of Poland in Finance, it has lower tuition fees and you start as a senior financial analyst instead of a junior.
You should do a bit more research. You might get a job as a senior in some third rate finance company, but any respectable institution will start you as a junior. Don't get too hung up on job titles in Poland - it's quite a common trick to give people grand sounding titles with a pathetic salary/responsibility.
A lot of Polish financial companies and Poland-based banks are looking for people with these language skills.
You're talking about BPO/SSC type places, which means you're talking about glorified data input positions. They offer very little in the way of career progression, unless you're willing to relocate abroad. Jobs in Polish financial companies go to Poles and foreigners with a sound grip of business Polish, not "amateurs".
Concerning my family and future children to be raised in a devout Catholic country with good and free education and multilingual parents
You're coming to the wrong country then. Poland is only superficially religious, and as for family - if you want a good corpo job in Warsaw, you won't be seeing much of them if you want the children to have a good upbringing. You won't be doing 40 hours and home - you'll be doing upwards of 50, plus work at home. If you don't want to do it, they'll quickly find someone else that will.
As for "good and free education" - you should perhaps spend some time in Polish schools before making that assumption. Schools are underfunded, teachers are paid significantly below average wage - the "free" education actually turns out to be quite expensive in the end.
By all means, come and see for yourself. But be warned, Poland is not a place for sensitive people, and you'll soon find that the Polish corporate environment is far less professional than you think it is.