[Zubersoft]

I would highly suggest you use the vertical scrolling display mode and set the page scaling mode to fit width. This should get you what you need as far as enlarging the page but having a smooth scroll without horizontal page turns. You cannot link the scroll speed to the metronome on a page-by-page basis unfortunately. The scroll speed is set up when the scroll initiately occurs, and it will not be recalculated for each page. 

To switch to the vertical scrolling display mode, load your song, tap the center of the screen, tap the display mode icon at the bottom to the left of the page scaling icon with blue arrows and then change the default display mode to vertical scrolling. Then tap the page scaling icon and change the default page scaling to fit width. You will want to do this in whichever orientation you are going to be viewing the songs, as you can actually set different display mode and page scaling settings per orientation. Give this a try and let me know if it fixes the issues you are currently having. I know you listed that you are using vertical scrolling, but it sounds to me like you are using the single page display mode in landscape orientation, and just happen to be scrolling vertically because the page is larger than the screen. Let me know if that is not the case.

Mike