Thank you for pointing me in the direction of Catalyst. Initially, I was thinking about doing this without using a Framework, but Catalyst looks to be quite flexible and I can see it saving me a lot of time.
Re^2: Is Perl the right language for a large web application?
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In addition to Catalyst, I would recommend that you also look at some of the newer webapp frameworks, such as Dancer and Mojolicious. Personally, I prefer Dancer, but your taste may vary.
Regarding point 3 in the original post, the #1 reason for you to choose Perl for this project rather than Python or Ruby is that you present yourself as already being significantly more proficient in Perl than the others. All three languages are more-or-less equivalent technically, so the most important criterion to consider when making a free choice between them is "Which one do I know and like best?"