67:  How can I replace highlighted text with what I type?

  Use delete-selection mode, which you can start automatically by placing
  the following Lisp form in your .emacs file:

    (delete-selection-mode t)

  According to the documentation string for delete-selection mode (which
  you can read using M-x describe-function RET delete-selection-mode RET):

    When ON, typed text replaces the selection if the selection is active.
    When OFF, typed text is just inserted at point.

  This mode also allows you to delete (not kill) the highlighted region by
  pressing DEL.