You have two different type of testing needs listed in your request for help. The first type of testing method is usability testing. The second type is sytematic.

Usability testing is performed by users. In the classes that I took, we constructed web pages out of construction paper and asked users to physically push buttons, fill in text, etc.. after they were given a specific task to perform. This allowed us a gauge on what the user perceived the functionality of the web site was. It also allowed us to ask them questions afterwards. If you get to ask people to use the application, ask them to perform a specific task. (Log on to the application and change your password) While they perform this task sit in the background and watch what they do. If they complete it successfully, ask them to rate it on a scale with the parameter that you are looking for. If they don't complete the task, find out exactly what stopped them from completing it.

Systematic testing is testing the system. Since you know how to use Perl, construct an app that makes demands on the system. Fetch a ton of database material while generating a bazillion web pages.......

I hope that this has helped, since that is my intention.

Good Luck,
fmogavero