Hello.
Not sure I can truly answer your questions, but I will give you my experiences.
1) It may be, depending on the disc. Sometimes I get full screen, sometimes letterbox. My screen runs a resolution of 2048x1156 (not the same, but up there) and it seems to have been hit or miss for most movies.
2) Not sure the video card will scale the movie. I do not *think* it will, but I am not sure it will not.
3) In the past, when I managed to stretch movies to full screen they did not become blocky or fuzzy or grainy or anything like that. They were clear, sharp and beautiful, the way HD movies should be.
I hope this helps you somewhat and, again, I know that I cannot answer from the perspective of your setup but I do think it will at least be similar.