[Typo3] PHP-Scripting - POST/GET under Typo3

[Frank Beismann]

Hi!

First of all, hello everybody! I´m new to this list, so please don´t be
mad at me if I don´t do things right the first time. 
I´m from Germany and I am running several Typo3-based homepages at the
moment. My current problem with Typo is this:

I would like to port a complete set of PHP scripts to Typo3. I know
there are several extensions that allow to integrate PHP scripts, but
apparently they do not support any interaction between a set of them
that would otherwise use POST and GET parameters to pass on values. Can
anyone give me some hints on where to start looking for possible
solutions and help me find a set of PHP scripts that pass on variables
amongst one another in Typo3? (I didn't find an extension, or a certain
tutorial/concept yet)

Thank you all in advance for your efforts!
Frank