If you want to see what pre-requisites a module has, use the CPANdeps website. Or download and install CPAN::FindDependencies and use the cpandeps script that it installs. Both allow you to fine-tune the results to match your version of perl.

There is, unfortunately, no way of declaring non-perl dependencies, such as those on external C libraries or external binaries, such that CPAN.pm can just Do The Right Thing. If you think about it, it's a Hard Problem, as different platforms have very different ways of installing such things. But I can assure you, it is a problem that people are aware of. If you have any good ideas about how to solve it, one of the module-authors or perl-qa mailing lists are probably the best places to discuss them.