I don't know about the specific issues you are having regarding using Netflix outside of the USA but it works for well me in the US.
However, you may or may not know that you need go to the Netflix website and log into your account and set up your "preferences" (types of movies, years, genre, etc.) so that Netflix will put those into the "recommneded" listing you get on your computer/TV screen via MC. The other categories you can select from, such as Classics, Comedy, Action Adventure, etc., are just a listing of available movies from Netflix but not adjustble per your "preferences". For example if you go to Comedies you will see old moves from the 40s and 50s (like Abott and Costello) even if your preferences are set up to only show movies newer than the 80s. Preferences only affect the Recommended movies list. Also you select the categories you want to see from the MC Options page. One last thing, when you upgrade/change the movies in your Instant Queue (changes made on the Netflix website) you have to restart the computer (or maybe just restart MC) to see those changes you made on the website.
The first time you activate Netflix via MC program, you will get a Netflix log-in page. After you log-in a Windows popup box will come up asking if it is okay to let this program run (or somethign like that). But I guess you are past that stage if your getting some movies to show.
The issue with the screen size being wrong sounds like something that happened to me a few years ago (back in version 17). I had to set MC to use a screen setting like 766x1024 (I forget exact numbers now) in order to get through the first-time Netflix setup then I switched back to my normal dispaly settings and never had this issue again.