I have a digital music desk and use Foxit pdf reader as it's very versatile, free, I can display two pages at a time and can open to fullscreen. I also had issues a while ago with Acrobat causing random static noises when I turned the page, which does not happen with Foxit.
For page turning I press a foot or thumb piston which generates a MIDI signal which is converted (via Bome's MIDI converter and Autohotkey) to a pageturn command. The trick is that you need to use a MIDI signal to trigger your pdf reader to momentarily become the Windows program "in focus" rather than Hauptwerk. Of course as soon as you've executed your pageturn you can click any MIDI key, stop or whatever and Hauptwerk goes back into focus, and it will still continue to play notes whilst doing the page turn.
See here for the exact scrips I use, all the software you need is free to download.
viewtopic.php?f=1&t=16262Regarding scanning music, I've not tried it for a few years but understood that it's very difficult computationally to "read" music so wouldn't set your hopes too high unless things have radically improved.