> I get the two errors:
> Constant subroutine main::DISPLAY_ID redefined at /usr/lib/perl5/5.10.0/constant.pm line 115.
>
> syntax error at config.pl line 176, near "1;"

it looks like you messed up something in config.pl. without seeing what you actually have in that file it's hard to say what.

> I don't really like the idea of having the configuration file publicly readable though.

you could change the owner of the files to whichever user apache runs as, probably www, or even better, set up mod_suexec.