Let me start off with a bit of my background:

I am a citizen of Poland (born and raised) but have never been employed there. I graduated from a U.S. university in May of 2012 and a month later began working for my current (U.S. – based) employer. After a year, my work authorization expired (F-1 visa, OPT), so I had to physically move back home, but am still working for the same company (waiting for an EB2 visa). There was a brief break in service of about two weeks between the end of my OPT and the day I resumed work upon arriving in Poland.
I am single, have no dependents, and no other sources of income (no retirement funds, investment accounts etc.).

Here are some of my questions:

1. In 2012, I only worked in the U.S. and filed a tax return there in the spring of 2013. Should I have paid any taxes in Poland for my 2012 income? If it helps, I was only there for less than two weeks in 2012.
2. For 2013, I received both a W-2 and a 1099 from my employer. Should I file a tax return in the U.S. for the second half of 2013, when I only worked and lived in Poland? The salary and a year-end bonus were not taxed in the U.S. (I was in Poland for exactly 180 days in 2013)
3. During the past several months I have transferred some money from my U.S. to my Polish bank account – mainly for day-to-day expenses. Should those funds be recognized in my tax return?

Any help would be greatly appreciated. Also, please let me know if there is any other information I can provide to help you answer my questions.