As far as the errors that come from connecting to the servers, you might try adjusting the list of servers your install of CPAN uses. You'll have to modify the urllist parameter in the CPAN::Config module. Next time you run a cpan install take notice of which servers you connect to more easily and move them up in this list.

Another possible source of the "redefined functions" messages is that some module that you are installing is redefining one of it's own functions during a test, etc. This isn't uncommon with modules that do dynamic function generation (Class::DBI, etc). Just a thought.