If you would like, you can try
http://www.litespeedtech.com/packages/lsapi/ruby-lsapi-4.0.tar.gz
It should be compatible with ruby 1.8 and 1.9 . Also it shoud fix the empty ENV problem.
In our cpanel setup, those functions are configured in httpd.conf with
please check permission of /usr/local/cpanel/cgi-sys directory and files in it. all user should be able to access those files.
APC does not work well with PHP suEXEC as each PHP process will use its own cache memory, not shared.
You should try eAccelerator + /dev/shm if you need to use PHP suEXEC.