Q3 your backspace is also "back" in microb. if you want more actions from your keyboard in microb get greasemonkey and TapScroll. with TapScroll you can move the screen left 'l' and right 'h', go to the top of the page 'g', page down a full page 'space' , half page 'n' , line 'j', page up a full page 'shift space' half page 'p', line 'k', and the one you were asking for back 'b' and forward 'f', there are also some onscreen buttons that let you go down and to the top of the page. to turn the on screen buttons off/on 't'.

hope that helps