Regarding the strict standards errors, are you still getting those after changing the server error settings?
And did you do the changes to the correct php.ini file (ee http://yourdomain.com/index.php/index/admin/phpinfo => Loaded Configuration File) and use this setting error_reporting = E_ALL & ~E_NOTICE & ~E_STRICT
The owner of cache can not be root. See the faq for details: How should file permissions be set?
In my server the owner has to be apache so that php scripts can write to the folder. But the correct user varies. It could also be www-data. Maybe these will help you find out what the user should be in your server:
https://forum.dokuwiki.org/thread/13409