Anything else beyond that, like what happens at Yahoo or whatever, needs to be done at the HTTP server level, which is out of my league.
I don't believe this is true. Sending HTTP headers is very simple, especially using the CGI module. It's also more reliable than HTML meta tags.
I highly recommend you browse the HTTP spec at HTTP SPEC. It's a bit dry, but it will teach you volumes about how CGI works. Then, the redirect method of CGI.pm will make perfect sense.