In order to keep your systems up to date and secure the yum tool is the easiest method of completing this, however without automation your systems can easily miss updates and become insecure. There is however an easy solution to allow you to setup automatic updates of RedHat/Centos packages using a simple bash script and cron job implementation.
If you are the only person who should be connecting to a server or are a member of a team who needs to audit who is logging into a server, you can easily have the server send an email upon login to a user account.
This should not be relied upon as a security measure, however it is a very good tool to confirm who/when logins are occurring.
Allowing the malicious users of the world more information than is absolutely necessary doesn’t make sense and is simply inviting them to run automated scanning tools to discover old and outdated versions of PHP and Apache before attempting to breach the system using known vulnerabilities with that version. Although it will not completely hide the fact you are using either system, you can easily remove the HTTP headers that are sent as part of every response by PHP and Apache, advertising their version number.
To reduce the security risk of your server, you should implement this, but remember that it will not hide the fact that you are using either software, it will simply not advertise the fact.