Scroll with vim-movement keys: h,j,k,l
To scroll pages with h,j,k,l keys (like vim), I’ve installed the firefox extension vimkeybindings.  With it, I can be working in a vim window where I use a lot the h,j,k,l keys, do Ctrl-Tab to switch to firefox window, and scroll around the firefox webpage with the same h,j,k,l keys, without having to displace my fingers to the arrow-keys and back again. I do this a lot, and doing it this way makes it much more fast/uncumbersome 🙂
Also, the default firefox shortcut for the search-bar is Ctrl-j or Ctrl-k, which complements very well with the vim-movement keys 🙂
 If you are a vim power user, there are other more-complex firefox extensions that bring more vim-power into firefox. The vimkeybindings is simple and a good match for what I want for the moment.
1 bar for url + search
To make firefox have only one bar for the url and search (like chromium) , I use omnibar