I guess I won't be getting many straight answers on this thread.
But to answer your questions -
My question is this, will I need a drivers license for the bike? The bike has a 150cc engine. I believe that is a different category of license than what you see a lot of kids riding around on in the country of Poland. Most of those, if not all, are 50cc's. I have a drivers license for Taiwan and I have an international driver's permit as well, which allows me to ride bikes up to 400 or 500cc's.
That'll be fine. You'll want to convert the Taiwan licence to a Polish licence, and you may have to do the theory test (not sure without checking - but it's easy) - but you can drive for a year on the IDP anyway. All rather simple and without problems, though it's advised to wait until you've been in Poland for 6 months before exchanging the licence.
What steps would I have to take to legally ride the bike in Poland?
You'll have to re-register the bike locally. This means that you'll have to export it from Taiwan and import it into Poland - it's not difficult, though there might be some (small) tax to pay.