There isnt Really any Standard behind the Dimensions of the Camera or the Holes, as in Mimicking another Existing Camera.
Its Just how big the Camera ended up Being.
The main Reason for the Holes being there is for Mounting the Camera to a Tripod or other Camera Support in "normal" orientation, Inverted Orientation, like for Crane Mounting or Ceiling Mounting, and the Side Holes are for 90° Rotated Mounting.
They can of Course be used to mount any Accessory to the Camera that you can make fit there, same for the smaller M4 Holes all over the Camera.
I Personally use the Top 1/4" Hole to Mount a Cold Shoe at all Times, which is a very fast way to Mount a Standard Field Monitor there, and to break down the Rig in a Short Time for Transportation.
.
If you need Lens Supports, probably the Easiest Way to achieve this would probably be to use an Adjustable Riser / Base Piece below the Camera
and use Standard Cine Rods and a Standard Adjustable Lens Support to fit whatever Optics You try to Mount to the Camera.
If being able to Remove the Rods and Support quickly is an Requirement, consider to Sandwich a Quick-Mount Plate in Between, like Arca-Swiss or Manfrotto (or whatever else System you might already be using for your Camera Supports).
.
hope, this Answers your Question!
