Apache2, php and threads

Hello,

i am plannung to develop a web application (actually an online game).
I have learned that php may use c++ classes from a shared library and
want to use this feature. I want to use apache2 and php 4.3.

So i think it is a good idea to make db accesses (to a mysql db) from
c++ to load objects from the db.

My question is: how to i handle the db connections? I think it is a
good idea to implement a static object inside the shared c++ library.
In its constructor the db connection is established. In its destructor
the db connection is shut down.

When the php script loads my shared c++ library the static object is
created, its constructor is called and the db connection is
established. When unloading the library the static object is
destroyed, its destructor is called and the db connection is shut
down. Is this a good idea?

I wonder how often my shared library will be loaded and unloaded. Will
it be loaded and unloaded for each execution of my php script? Or will
it be loaded once only and stays in memory for a certain time?

Is there one process for each php script execution? Is the process
shut down after the php script exits or does the process execute not
only one, but many php scripts? Is there a difference of using php's
dl command to load my shared library to compiling my shared library
into php as an extension?

How many threads will use the shared library? Has it to be thread
safe? Is it wise to establish a pool of db connection inside the
library?

Perhaps these questions are stupid. If there is an easy solution for
the problem of db access from a shared c++ library used in a php
script please let me know.

Thank you very much.

Best regards,

Christian Neise.