I believe that I can help. (please forgive me if this is something you find obvious)
** To remove/close out of your popup/page, look down at your status bar (the black bar with the wifi, battery, clock etc). Near the center of the status bar, there should be a "turn around/back" arrow box.
If you click that arrow, it should close the annoying popup/page and you will be right back to your content without having to hit the nook home button or reopen any programs.
Hope this helps. If you have any trouble, post here or send me a message. I will help if I can!
The "Media Bar" can be activated in the settings menu. If that is the "tiny touchscreen" you are missing.
Unfortunately, most screens don't have a 'Back' icon at the bottom, which I think is a design problem. If not, you might try flicking to the left on the black icon bar at the bottom of the screen. Try not to start on an icon, though. That will usually do a 'Back. It won't always get you out of a pop-up box, though. Which is why I have suggested that every pop-up box should have some way to escape, rather than choosing something that you don't want to do or hitting the 'N' button.