1. Would I still be paying fees as an international student?
You will not be a foreign student as you have Polish passport,all you need is the national ID.
One of my kid wanted to study in Poland but the education is not accredited in the US,they would wasted cpl of years and money to get that done after graduating.So it depends where do you want to live in the EU or Canada,
I want to work as a nurse so which route would be more beneficial?
I would complete my studies in Canada and then decide where I want to live and work,again thats me.