C-r is reverse-search-history. You press C-r and start typing your search pattern to trigger an incremental search. Most recent command matching the pattern anywhere in the command is selected.

In contrast, history-search-backword requires you to start typing your pattern followed by the keystroke it was bound to. The most recent command that starts with your search pattern is selected.

I think it's different. With these ones you can start typing a cmd, say 'dd ' and then hit up and it will got through all of the previous commands that started with 'dd '.

    "\e[A": history-search-backward
    "\e[B": history-search-forward

I'm on a mac using iTerm so I also have:

    "\ed": backward-kill-word

and have added a shortcut to iTerm to send escape-d when I hit alt-delete. It's like a softer version of ctrl-w, which I've found indispensable since I started using it. It's actually more consistent with the standard Mac alt-delete

no, by default ctrl-r searches through your history based on subsequent keystrokes. although if you're good with it, it's just as fast as up/down arrows.