The fatal error looks like it could be to do with an ereg overflow due to the new limits on php 5+ restrictions which are set to low (php preg_replace() can cause this), try adding this to the index.php:
if ( @ini_get('pcre.backtrack_limit') <= 950000 )
@ini_set('pcre.backtrack_limit', 950000);
if ( @ini_get('pcre.recursion_limit') <= 350000 )
@ini_set('pcre.recursion_limit', 350000);
I can't see the full text for the other errors in your post however.