The artistic, aesthetic part of it is pure creativity. We all think differently and that is the beauty of art. Something comes out of your head & ends up on paper, canvas, bronze, etc…
For example to do a silhouette of a person, I would start with the person and think of the things that make them who they are, their desires, passions and likes. Then choose objects that reflect who they are.
As for the technical aspect of it. The first idea could be done very geometrically in a simple CAD system. The other 2 are truly 3D and would need a bit more horsepower.
For the first one, start with the image you want to develop. Establish the light source, perspective point.
Place the objects where you want them, then copy them to the position where they will sit and scale them to produce the desired results.
Correct (for at least one artist). We had an installation at a visual arts center (a college’s community outreach/gallery) where this was done — the artist simply hung a series of strings from a fixture on the ceiling, set up a projector as a light source, took a stack of Polaroid photos, used a hole punch to punch holes, and began hanging them — when they ran out of pictures (apparently the space was larger than the previous installation), they used a Polaroid camera to take some additional photos which were then hung so as to be among the first viewed when examining the piece.
Yes. If the objects were all the same height, they would all need to be placed the same distance from the edge of the shadow they seek to create. Varying the height would allow longer shadows & let you move the object further away from the edge, so they appear more scattered.