What makes it possible to read YenPlus on a smaller screen is the way that it easily zooms to 100%. But it would be possible for SJalpha to leapfrog YenPlus and become the easiest online reader for smaller screens, other than GuidedView readers.
(1) The options menu right now is 2page and 1page. Add FullHeight and 100% options. FullHeight is the way it works now, 100% would start each page at 100% zoom.
(2) For zooming, hold the top edge of the page on screen, because you normally want to start at the top, and if the right edge gets to the edge of the display, hold it there. That keeps the top right hand corner of the page in view, which is where you normally want to start. The right edge will normally only kick in if 2page mode is picked.