Apache httpd 2.4 default layout (apache.org source package):
ServerRoot :: /usr/local/apache2
DocumentRoot :: /usr/local/apache2/htdocs
Apache Config File :: /usr/local/apache2/conf/httpd.conf
Other Config Files :: /usr/local/apache2/conf/extra/
SSL Config File :: /usr/local/apache2/conf/extra/httpd-ssl.conf
ErrorLog :: /usr/local/apache2/logs/error_log
AccessLog :: /usr/local/apache2/logs/access_log
cgi-bin :: /usr/local/apache2/cgi-bin (enabled by default, but some of the bundled scripts are 644)