[CentOS] Apache and PHP

Sorry for the newbee setup questions, but...

Should PHP be already setup with apache on the centos server install??

It's just that I can't get PHP working at all. It's 100% me, I just
don't have enough experience.

There is already a PHP.ini file, if I add any php modules in apache conf
and run httpd -S is says it's already running a php module.

I am using vhosts.  I did start by trying to use/install suphp as I'm
trying to replicate another server but when suphp engine is on I get a
500 error on .php pages.

If I take out all my suphp from the apache conf, it trys to download the
.php file rather than running it.

What's the best log file to trouble shoot this??

Thanks in advance, Mark.