Is this right?
Added a folder to the /public_html - is that the root?
bar/foo.php
Yes that it is. You can see, it is giving error :
http://www.ppsllc-us.com/bar/foo.php
It is probably not WordPress specific. You can rename the .htaccess to bak.htaccess and reload http://www.ppsllc-us.com/bar/foo.php ; if still it gives error, you need to contact your web hosting company's support. They might be upgrading some server software.
Regarding PHP error log file, its location and existence depends on server OS, setup etc.
Added a folder to the /public_html - is that the root?
Yes, public_html is your web root.
The most logical would be to check whether PHP is running or not from Command Line Interface. That however will need root access.