I battled php5 apache2 mysql, and finally I found that
LoadModule php5_module /usr/lib/apache2/modules/libphp5.so
was not added to apache2.conf automatically by the
apt-get install libapache2-mod-php5
procedure. Maybe this is a trivial fact that everyone but me would know beforehand? Anyway, adding the LoadModule line above fixed my problems.
Also, that web browser caching deal sounds like a nasty little way to obfuscate any headway that someone might be making while trying to get this all working.