Navigation location and long pages

I’m not sure if this is a theming question or not, but I have two related questions:

Are there any themes (or plugins?) that help with book navigation on longer pages? Specifically:

  • page navigation (prev/next) at the bottom of pages
  • some kind of floating navigation bar?
  • some kind of next/prev available at the left and right side of the page at all times

Something to handle navigation short of constantly needing to navigate back to the top of the page?