In the 'Free Graphics Set' folder, 'Buttons' there is a transparent png file. It is small, but you can resize, and you won't actually see it on the UI.
It works exactly the same way on a button press yes.
And yes - the large transparent button must be 'behind' the other buttons, but you can do that with the 'send to back' option on the leftmost menu. Or you can just have a smaller defined area not covered by other buttons on which to swipe.
Any subpage can scroll - by making the scrollable height/width smaller than the total height/width.