php version difference - local installation very strict

Hi all, It seems that the version on my local apache installation is more strict than the version on my production server. How can i counteract this without potentially having to upgrade 300+ pages in my entire app? is there a setting in php.ini that i could locally kill some of this debugging info? Some examples of errors i'm getting locally: Notice: A session had already been started - ignoring session_start() in %siteroot%\admin\menu.php on line 9 Notice: Undefined index: success in %siteroot%\admin\menu.php on line 18 Warning: Cannot modify header information - headers already sent by (output started at c:\inetpub\www\tommiezito\admin\data_entry\start.php:14) in %siteroot%\admin\data_entry\start.php on line 37 these errors are foreign to me as i have combed my code 100's of times before i deployed my app online 3 months ago. do i NEED this newer,stricter version or can i install a deprecated one? any help would be amazing. ~pj