How to validate the .emacs config file immediately?

M-x eval-buffer

How to highlight keyword?

(global-font-lock-mode t)

How to activiate region highlighting?

(setq transient-mark-mode t)

How to prevent the creation of backup files?

(setq make-backup-files nil)

How to change font type & size?

Simply press Shift and the first mouse button.

How to save a shell session?

script

How to "word wrap" in Emacs?

Basically,

But of course it doesn't tell you how to actually use "C-x f".

If you just type "C-x f" you get this error: "set-fill-column requires an explicit argument"

To set the line wrap to 80 for example, type 'C-u 80 C-x f '

For more information on word wrap, see word wrap (filling)