In emacs it is easy to define custom commands and bind it to keys. For instance, if you add this to your init file:
(defun open-shell-at-left ()
(interactive) ;; Tell emacs this function can be called interactively
(split-window-right) ;; Just what C-x 3 does
(shell)) ;; Just what M-x shell does
(global-set-key (kbd "C-c 3") 'open-shell-at-left)
You will have what you want when you type C-c 3. In general, you can find documentation about what a key binding does by typing C-h k and the keybinding. From that point, it is easy to chain existing commands into new ones.