Finding out current PHP memory limit and php.ini location

To find out the current value of PHP memory limit, navigate to status report (Reports > Status report, http://example.com/admin/reports/status) and scroll down (items are listed alphabetically) to PHP:

Two lines above that, you can see PHP version info; 'more information' link takes you to phpinfo() page, where you can find out the location of php.ini file:

(example from a Linux (Ubuntu) system)