My 2 cents - from having zero knowledge to running a website...
Ok - I don't know if there's a specific reason that you're using apache 2, but if there's not why don't you remove the stuff you've installed and try this approach (the one I used to set up apache/php/mysql on my server).
I'm going to assume that you have 10.3, and are not using the server version.
Most of the software you want to run generally needs to be compiled to 'work'. I don't know where you got the packages, but there are only a couple of places you can get "pre-packaged" php and mysql. Apache 1.3 already lives on your system, along with other goodies you'll need for running a server like a mail system (MTA - SMTP) called Postfix, a text editor called Pico (easy) or Vim (advanced). You'll need to know how to use the command line or terminal, which is Bash if you're on 10.3. All the config files for these servers are text based, and are in locations hidden to the Finder (although BBEdit can 'see' hidden files, one of the best editors in the world if you're serious).
Setting up these server packages is not just a piece of cake (unless you have OS X 10.3 server I think...). I was learning from scratch, and fumbled my way through. However, if you read, and google you'll learn heaps and (probably) perserver

. When reading about how to set things up always remember that something written for Linux or BSD will also most likely apply to OS X as well.
OK - first step. Marc Liyanage has done most of the hard work for you, by packaging up PHP and MySQl (or, he may not do the packaging anymore, but he does have excellent instructions on how to set up your system and links on where to get the packages). Go to his home-page
http://www.entropy.ch/software/macosx/ . Now, the packages you want will probably only work with certain versions of Apache. They'll will probably also depend on a specific complied version - namely the on that ships with OS X 10.3, which is an Apache 1.3 - NOT 2. Again, if you really need to use 2, then you're probably on your own. Apache 2 is not really better than 1.3 in any way, and in fact they're both being actively developed at the same time. Apple also releases security updates to the standard installed Apache with the software updates - it's a much easier way to stay secure than downloading and compiling your own patches.
That's all I've got time for at the moment...start with Marc's page and go from there.
a.
(late comment - Marc does link to the PHP 5 package for Apache 2 on his page. Make sure you have that one, and not the one for Apache 1.3)