First, the question makes no sense. It presumes there's one CD drive, no more no less. That's often not the case, especially since many USB keys appear as CD drives to the computer.

It seems that the real question is that you want to locate the installer, and from there the files to install. You can find the path to the installer via $0

use Cwd            qw( realpath );
use File::Basename qw( dirname );

my $path_to_installer = dirname(realpath($0));
[download]

As for your second question, look into qx, documented in perlop