There have been a few issues that have been cleared up regarding financial aid (specifically Stafford loans). These were based primarily on bad communication on the school's part and Sallie Mae's part. All students from my class who applied eventually received their loans, but they had to cover expenses themselves at first. This was my experience, but it certainly does not apply to many of the other students.
If you are considering Warsaw, I suggest you ask as many questions as you can and DO try to visit before matriculating. The city is a very different environment from what many students are used to in the US, and there will most likely be a bit of a culture shock to those that have never been outside of the US. Some might regard this a good thing, as it is just another experience which will potentially lead to personal development and worldly insight. The same applies to almost all eastern European schools/cities though.
The English program here is a very solid one, as the six-year program has been around for awhile, and was a launching pad for the four-year program. They take a lot of pride in their eduction and always work to improve the quality of the program (especially with the new dean of the English Division).
As for the transfer question. I know that students have transferred individual credits in the past or entire academic years. I personally know students who have been exempted from immunology, biochemistry and a few others due to previous courses they have taken. You would need to talk to the program head of that subject (and the dean's office) and provide documentation you have had these courses and they might have you take a test or just talk with you to make sure you are versed in that area. Many professors treat the education here very seriously (a very good thing) so they want to make sure the students they are graduating have the proper knowledge expected of a good doctor.
Hope that helps!