I've always used mod_perl as lean and as mean as possible, so I can't tell you what CGI::xx or ModPerl::Registry does or doesn't do.

However, I've found the mod_perl mailing list to be very responsive to questions. Maybe you could filter back some of the good answers to the Monastery?

To answer one question I think I do know the answer to:

...ModPerl::Registry overrides perl's core exit() function, so that the interpreter is not actually exited. Is it still safe to use exit() as a "stop executing code here" way of thinking?

That's why exit() was overwritten. So you can use exit() as a "stop executing code here". I've used a similar approach in Thread::Exit, which allows you to exit a thread rather than exiting the entire process, taking down all other threads with you.

Hope this helps.

Liz