My workaround (thanks to you, taller) is to use the cell's alt text to store a ID tag and the path of the image. This can then be read as the cell's formula property. I can count the images by looping through a range and looking for my ID tag using instr and can have the path and filename (extracted from the path) as needed.

When a picture is placed OVER a cell, I save the name which shows up as a shape (only while placed over cells). I use that saved name to place the picture back in the same cell:

ActiveSheet.Shapes(SavedName).PlacePictureInCell

Until we have better developer docs and more object properties, this will be OK.