Your answers may or may not influence development of Postmill.
Basically, I'm redoing the way submissions are retrieved (which will bring back top/controversial sort modes, introduce a new 'most commented' mode, and allow people to blacklist forums and users), but implementing a 'previous' button is hard. If people can live without, it will make my life a lot easier, and cool new features will arrive faster.
Edit: the changes are live now. The filtering stuff comes later, but 95% of the work needed to implement it is done.