DLP and eDiscovery work for the project sites the same way as for any other SharePoint list and document data. Project data (schedule, project fields, business drivers, etc.) is not covered by this. Integrating project data using the Business Connectivity Services will render data available via the SharePoint Search, but it is not easy to impose data trimming on that and also it is not available for eDiscovery. To enable auditing of project data you need to setup a custom solution that tracks and archives information. It depends on your auditing needs if this is a simple report or something complex.