No. It works in Safari or Chrome on your phone. Add it to your home screen to use it like an app.

Put the page on a darker table, fill most of the screen with it, hold the phone flat above it and avoid your own shadow. Good light helps the text recognition too.

Clean gives white paper and dark text, like a scanner. Colour keeps colours natural with the shadows evened out. Black & white is like a photocopy and makes the smallest files. You can switch at any time; the original photos are kept until you close the tab.

No. They're cleaned up and read on your phone, and never leave it.