Hi davpunk,
Ad 1) You just need to edit C:\Program Files\WebHelpDesk\conf\labels\Labels.properties or create your own following the README file in the same directory.
Ad 2) You can hide request detail in settings of each Request Type. You can also hide Priority in Setup -> Tickets -> Options.
Ad 3) Hierarchical custom fields are now not supported. It would be a feature request.
Hope that helps,
Peter