can anyone tell me some things about the daily Polish life and what we should prepare in advance?
If your husband is Vietnamese, he should have a visa to legally work here.
Perhaps his employer could help him, if he does not already have one.
Then he will need to get a P.E.S.E.L number.
I am wondering if I should buy him an ipad mini or an iphone as a means of communication when we are apart.
I recommend Skype, it's free to download onto your computer or smart phone and calls are free between two computers or smart phones with the downloaded software.
There are other cheap ways of contacting each other too.
what is more common currency between U.S dollar and Euro?
Just to clarify, Poland has the Polish Zloty.