Absolute Directory path definition

I am a newbie with cPanel and web design in whole. I designed my website using WAMP (windows Apache MySQL and PHP) on my computer. I used to the following statements in my intialize function to ease refrecning of including files.

PHP:

// DIRECTORY_SEPARATOR is a PHP pre-defined constant
// (\ for Windows, / for Unix)
defined('SITE_ROOT') ? null : 
    define('SITE_ROOT', "C:".DS.'Wamp'.DS.'www'.DS.'ASL'.DS.'coastaca');

defined('LIB_PATH') ? null : define('LIB_PATH', SITE_ROOT.DS.'includes');


I thought the below changes would keep it working.However it doesn't seem to be working.

PHP:


defined('DS') ? null : define('DS', DIRECTORY_SEPARATOR);

defined('SITE_ROOT') ? null : 
    define('SITE_ROOT', DS."home".DS."coastaca".DS."public_html");

defined('LIB_PATH') ? null : define('LIB_PATH', DS."home".DS."includes");


1. I thought it should be fine to leave my include file out of the public_html as it has sensitive scripts. I suspect the webpages would still have access to it?
2. The first time i tried setting it up it displayed php errors however now it it just displays error 500 internal problem. I would really like to be able to see the errors when i try access my .php pages from browser.

Does anyone know what i should do?