Having used a shared server to host sites for a while (and had the latest version of PHP automatically installed for me), I now have my own dedicated Redhat Linux / Apache server and am responsible for updating PHP myself, as and when I deem it necessary.

Due to the recent security hole discovered in many older versions of PHP, it would seem that now would be a good time.

My questions are:
1. Would I be correct in saying that there's no such thing as an 'upgrade' in the sense that to 'upgrade' PHP, you're actually reinstalling the latest version completely over the old one?
2. Does anyone know of any nice, cuddly, online 'idiots guides' to helping someone like myself install the latest version of PHP (with mod_ssl) on my server?

Thanks for your advice.