You're in luck. Been there, done that, have the battle scars to proove it.
I don't know what the Apache-AdvancedExtranet thing is. Never seen that before.
Start with regular old Apache. I'm using 1.3.28, haven't used 2.x yet. Get that downloaded, then head over to PHP.net
. They have some good directions on how to compile Apache and PHP.
When I compiled PHP I used this in a configure script
./configure --with-apxs=/usr/local/apache/bin/apxs --with-zlib --with-jpeg-dir --with-gd=/usr/include --with-png-dir=/usr/lib --with-mysql --with-ldap
If you do all that Apache and PHP should be playing well together. You can test it by making putting a file in your DocumentRoot, name it something.php. The contents of it should be
When you pull that page up you'll get a big page of information about PHP.
There should be some good instructions in the PHProjekt for getting it installed. I've installed it myself and don't remember it being really hard to get going.