Code-questions on SF tend to be focused on scripting and automation, and even those are getting foisted off to SO these days (they didn't used to). Information Security questions relating to code-specific items used to be somewhat topical here, but they're now going over to security.stackexchange.com.
In general, SF is more about installation, configuration, and automation. For something as general-purpose as PHP:
- Installing it to a production server: ServerFault
- Installing it to a home server: SuperUser
- Digging into exactly how a security fault is a fault: Security
- Figuring out how to code around a fault you can't fix right now: StackOverflow, or possibly Security.
- Installing modules: ServerFault
As for Wordpress, there is a Wordpress StackExchange site just for that. Though even they punt install/config stuff back to us.
One thing I forgot to note is that our faq (currently) leads off with:
Server Fault is for system administrators and desktop support professionals, people who manage or maintain computers in a professional capacity.
It's the 'professional capacity' thing that trips a lot of people up. We're not about general server stuff here, we're about specific problems that arise in the day to day work-place of systems administrators. This is why people with servers in their home find their questions shuffled off to SuperUser, even though the answer would be nearly identical had it been in their workplace.