> How do I find out the name of the current major's mode key map? Say I
> want to add a new keybinding that I can use in the "find-file"
your question and your example doesn't match. When you are in mini buffer, a minor mode is in effect. In this particular case, it is minibuffer-local-map.
anyway, here's a page describes exactly how you findout a major mode's name and its key map name (if any), or what key map it actually uses. Also a example about minor mode.
• How To Reclaim Keybindings In Emacs