If you can get a pdf version of Mannheim The Rolleiflex SL66 Way, you can see some diagrams of various setups, including bellows, microscope attachments etc. The file I have is 113,900,000 bytes, so I can't email it!
One of the most useful things that often come with these cameras is missing, the mount for other third party lenses, such as large format lenses or Imagon, although if you wanted one it looks like it could be improvised from some of your bits that have a bayonet fitting like a lens bayonet. I have a bag of bits similar to some of yours, some of which I can't identify either.
R3 looks like part of a bellows lens attachment, with a cable release to allow auto aperture closing for a lens attached to a mount separate from the camera.
As the previous poster says, R7 is a tripod mounting clamp with a universal Arca-type plate. I modified an off-the-shelf plate to fit the camera snugly so I can use a similar clamp. I have found it more stable than the Rollei tripod mount that fits into the wedge arrangement on the camera base. I can post a photo if you're interested.
You will enjoy your SL66! It really is a gem of a camera.