I bugfixed my code... I shouldn't post untested stuff! It seems to give what you are after. graff and johngg have also given you good approaches, so hopefully you are all set now.

It seems like getting the data wasn't the problem, but creating and navigating complex datastructures - whenever I am having problems like this, i find perldsc and perlref very helpful for avoiding frustrations! And as far as deciding on the most appropriate datastructure, that is really down to experimenting and seeing what works for you!