How to properly turn off REVISIONS and AUTOSAVE for whole site and optionally for a custom post type only

This should be placed in your wp-config.php (and no where else):

define( 'AUTOSAVE_INTERVAL', 60*60*60*24*365 ); // Set autosave interval to 1x per year
define( 'EMPTY_TRASH_DAYS',  0 ); // Empty trash now: Zero days
define( 'WP_POST_REVISIONS', false ); // Do not save andy revisions