Check out this free documentation WordPress theme called weDocs. http://i2.wp.com/tareq.wedevs.com/wp-content/uploads/2014/01/screenshot.png
Sublime Text 3 all the way!
+1 html5 apps are awesome
Try the mobile-first approach, its easier to maintain and for breakpoints it actually depends on the design.
Maybe there are similar themes in the market place that’s why they rejected it? And submitting the HTML version first will save your time and energy.
And for improving the design, i wouldn’t use bootstrap for such a simple design, too many HTTP requests.