Still confused by Permissions - linux, nginx, php-fpm

Solved:

php-fpm doesn't run as the nginx user of course. It can be configured (in CentOS) in the file /etc/php-fpm.d/www.conf. I edited its config by adding line 45:

44  ;group = nobody
45  group = webadmin

Then restarted it:

sudo /etc/init.d/php-fpm restart