When you rotate a group object, individual objects linked together will also be rotated. If you wish to rotate only a single object, then right-click that object and click Deep Select or left-click the specific object in the Project BrowserTree.
When multiple objects are selected and a rotation is applied, the rotation will be applied with respect to the center of the combined objects. Specifically, the mid-point of the top-left object corner and the bottom-right object corner will be used.
When you flip a group object, individual objects linked together will also be flipped. If you wish to flip only a single object, then right-click that object and click Deep Select or left-click the specific object in the Project BrowserTree.