How can I make it so that when I press C-xC-b to access the Buffer List that that buffer automatically takes focus instead of having to switch to it manually with C-xo? I can't find a variable that customizes this.
You can replace the command
list-buffers which is run with
C-x C-b to a function that does what you want. In this case
buffer-menu-other-window opens the buffers list in another window with focus. Adding the following snippet to your init file should remap
C-x C-b to the new function.
(define-key global-map [remap list-buffers] 'buffer-menu-other-window)
global-map represents the keymap where
C-x C-b is bound to a command,
list-buffers the original command and
buffer-menu-other-window the new command.
An alternative is to switch to ibuffer, which does not share this problem.
ibuffer is part of GNU Emacs, so on recent versions of Emacs you should just need to add
(global-set-key (kbd "C-x C-b") 'ibuffer)
to your init file.