Whatever is viewable is a page. Like in books it's continued next page. Don't worry about the fact that you seem to be PhotoReading two sections of the article at the same time. Have an incubation time to let the mind sort it out. If you consciously know that the text is missing and will be viewed in the next jump then the nonconscious knows too. No reason you will have problems with activation. It might be a mini second or 2 slower but nothing serious.
Scrolling only moves up one line at a time and causes flicker. Ir's slower because the mind is repeatedly seeing an earlier part of the page.
Page down producces crisp jumps like flipping the pages.
In Adobe find the comfortable screen size, there are some defualt figures in the lower left but you can overwrite them with your own percentage. 75% might be awkward but 83% workable yet that figure is not one of the defaults, just overwite it in the toolbar.
As for seemingly small font size. I will often PhotoRead it smaller than I use for activation.
Alex