Willie Jackson on "[Plugin: W3 Total Cache] How come it tells me "No package XXX available" when I try to install?"

Try:
yum install php5-pear php5-devel // (note the '5').

As for httpd-devel, check your /etc/yum.conf file and make sure that the line saying 'exclude=' line doesn't contain 'httpd'. If it does, remove it and try the command again.