> Add to that the fact that my Polish teacher's explanation for many things is "there's no rule, you just have to learn what sounds right." In one case, if you have a masculine noun you must either add an a or a u on the end. There is no rule for which.

I can only sympathise with you, but that is the thing. As native speaker you just know when the words sounds good or off.

One good thing is that you can always read Polish words phonetically. The notation to sounds is always the same. So its something :)