Can you exchange Canadian $1000 bills at kantors in Poland?
Also what are your suggestions when opening up a bank account, should you open one up in EURO currency, or all in Zloty currency, or half of your money in Euro and half in Zloty currency.
CAD is not the most popular currency, it all depends on in which city you'll be - no problems in a big one, I guess.
Many bigger kantors have their online sites, so you can search the prices (skup = buys at, sprzedaż = sells at - sometimes those price refer to a minimal amount, like for example 1000 euro).
Google search for:
kantor "dolar kanadyjski" skup
If you find a kantor in the place you're going to, there should be some contact details (e-mail, Skype, phone number), write to them and ask about it.
1000 bills (Canadian dollars) = banknoty tysiącdolarowe (dolary kanadyjskie).
When you exachange bigger amounts (different limits in different kantors) of cash, you can negotiate prices.
And please be careful, if some muggers notice you with big amounts of cash, it may be dangerous (I guess it can happen anywhere), for example 5 bills of CAD 1000 = 13200 PLN = 66 bills (as 200 PLN is the biggest bill in Poland), so even if enter the kantor with a few Canadian bills, you will leave with your wallet full.
Also check the Polish/European/Canadian limits for importing/exporting cash, if I'm not mistaking bringing in/out more than 10,000 Euro (or equivalent in other currencies) requires a customs declaration.
The currency of your account depends on the purpose of it.
If you're going to use this money only or mostly in Poland then I don't see any need for Euro account, but if you're going to regulary spend some significant amounts in Euro (buying in Euro-zone, frequent travels) then of course an account in Euro could be useful.