Why Mobi, that is so old school. AZW3 offers all the power of EPUB2.
there is a plugin called
hyphenate this that might help
Pages! ebooks have screens of various size and variable sized text.
% of a section is more meaningful than how many forward taps you did
One of the features of my K4, was the progress bar at the bottom. The dots were the 'chapter' entry points. the arrowhead, the point you started the current book view session at.