It seems that you've thought this through enough that your ideas sound solid enough to me. Interacting with DBMS is no big deal in Perl, especially using DBI. Indeed Programming the Perl DBI is a fantastic book for a Perl user who is wanting/needing to learn how to interact with a database. I used this book on my first database/perl project and it was easy to use as a learning tool and as a reference later on.

As far as traps go, the only thing I would take time to consider is the use of MySQL as your database of choice. I personally use MySQL for home projects, but it does have some features that are lacking in other production-quality DBMSs. In general, people recommend Postgres as a more stable and more powerful database system. Depending on how many users, how frequently they'll be interacting with the database, etc.... you may want to look into using Postgres instead, or at least benchmarking the too with some sort of simulation to find out which one better suites your needs.

Cheers,
~CS