Does QGIS preserve Feature Class Relationships (1to1 or 1to many or Many to many relationships) and can the related attributes be clicked and viewed through the identify feature tool?
Sort of. It doesn't transfer them from an ESRI relationship class in a geodatabase, but you can relate them in a QGIS project. Here is a good link that helped me with my project. http://blog.vitu.ch/10112013-1201/qgis-relations I haven't yet found a way to maintain that relationship from Arcmap to QGIS, but the information contained in this website allowed me to relate my data table within a QGIS project.