Working with PDF Files, Cropping, Scrolling (Classical Scores on Screen)

I am very new to FCP and need some help working with approaches for getting scores on the screen. I am making some educational videos that focus on classical music. I want to show a score (sometimes more than one) while I play the piano. I am trying to create a situation where I can move through a PDF as the music progresses, while using shape masks to mark off the rest of the PDF.

In essence, I'm trying to do the following:
1. Keep the piano on the bottom part of the screen.
2. Have three separate score layers above, which I've cropped from full size PDFs with shape masks.
3. Move through the PDFs (with keyframes?) as the music progresses while keeping their shape masks in place.

This isn't really working, however (See the attached image to give you a better idea of what I'm trying to do). I'm having several problems:

1. The image quality of the PDF downgrades too much. I recognize that FCP does not use the PDF as a vector graphic (which is what it was), but I saw somewhere that you can do something in Motion to fix this. I do not have any familiarity with Motion (yet), so I'm not sure what to do about this. Perhaps I should export each PDF page as a massive PNG file?
2. I'm having trouble moving the PDF separately from the mask--is this possible?

Is there a better approach for this? Thank you for any help in advance!

Verify in the Viewer's menu if you're set to better performance or better quality. FCPX will degrade an image only during playback if necessary to provide smoother playback.

So you crop or whatever and have piano in the lower part of the screen.

I'd resize the what you really need and convert the PDFs to PNG files, as I find them easier to work with.

I'd place a Adjustment Layer clip (plenty of free ones to download all over) above the score clips, apply crop, and mask to it. You'll want to put that and the score clips inside of a Compound Clip so it doesn't affect the piano clip.