RPM : Is it possible to relocate a RPM package to multiple..

Hi Everyone,
I am new to Linux and working on creating RPM
Packages.
The software prerequisite checks for our product include Apache and
Java.
How do I check whether these are installed or not . I cannot check
these dependencies using package names as they may or may not be
installed thru RPM . If they are not installed thru RPM then package
will not exist in RPM database . So how to check for these software
dependencies?

Other Question I have is ,

While installating RPM, I have to take user input on the apache
installation directory as I need to copy specific files under modules
folder of Apache installation directory . I am using Prefix tag to
specify the installation directory of our product . How to take user
input on where Apache is installed and use it in RPM to copy apache
specific files to apache installation directory.


Thanks & Regards,
Veda