RLO Documentation
The Open RLO File shelf tool will search for a Maya file in the pipe that matches the selected shot and open it. If one is not found, it will duplicate the currently open file (ie a previs file) and save it as a the new RLO file. It will then set the timeline, and import the environment published from Houdini based on the Time and Set attributes stored in ShotGrid.
If shot-level changes need to be made to the environment, you can simply transform objects in the environment as needed. When you save the file, an override file will also be saved out of the tweaks you made to the layout for that shot. If you need to remove an object, right-click on it in the outliner and press Deactivate Prim.
If changes need to be made that will affect many shots, the layout should be edited and re-published from Houdini.
The Pin Shift tool is from Craig's team at Premise. It will shift animation curves backwards and forwards on the timeline. This should help you line up animation from a previs file to have the correct starting timecode (1001).
The Publish Camera tool will take the camera you select in the dropdown and publish out a USD file with the camera in it to the pipe. This will be later imported into Houdini and Maya for animation, FX, and lighting.