Anyways I appreciate the feedback!
Yes, OnSong costs money because of all its features. You can create set lists, it'll do automatic updating of key changes (singer wants to do song n A, your version is in G, no problem), searches by song name or artist name - all in your device/memory card. It'll also access online music tabs via wifi (Ultimate Guitar, etc).
I forget the one I downloaded onto a tablet, tried it out once, that's when I realized I can't just put a PDF or Word document in and use it with scrolling because of the spacing I already mentioned. The solution to that is not to use scrolling, to 'push' the document along as you go through it, unless you have the Bluetooth pedal advancer. BTW, I see people do this all the time at open mics, not so much at gigs.
From what you're saying, you're just setting this up for home computer use at this point. Maybe you've seen requests for this use?
Hey, I'm just trying to save you some (wasted) time - take a look at the Google Play store, there are dozens of apps, many of them free (because they contain ads of course).
You're right about 'trusted websites' that access someone's files - but you don't have that - no one knows who you are and no one with any smarts is going to allow an unknown website to access their files! I'd recommend that it has to be 'stand alone - a downloaded program, not run remotely.