Apache
Installation
The modules are generally under "mod_*". For instance, SSL support is in mod_ssl.
Configuration
The config file live under /etc/httpd/conf/httpd.conf. The various modules and plugins install a config file in /etc/httpd/conf.d. Note that the default httpd.conf has a line that reads:
Include conf.d/*.conf
That will read in whatever you have installed in /etc/httpd/conf.d
Logs
The logs live under /var/log/httpd. The "error_log" records errors. "access_log" records access.