Good points, I would definitely recommend looking into Selenium (http://www.openqa.org/). It's a tool that lets you record a browser session and then export it as a test (you can export to a number of languages, including perl). The tests can then be rerun at any time to make sure you didn't break anything. It's not only good for automated web interface testing, but also for things like populating a new install with data so you can run your tests against populated systems.