Are there any design rules when using heat set inserts? I realize this is mostly dependent on type of material and intended use.

Final design will be ASA-CF with the inserts being used in a side load instead of tension.

How far from edge should be considered minimum? How thick should wall be? Can opposite end of insert be showing?

Here is an example would be used in a cube to mount it to a surface. Yes this is extreme but I couldn't find something smaller. Just interested in the side fasteners. Mine would probably be M4x8.1 or M5x9.5

DUH!!! Need more coffee. I found the info I was looking for on CNC Kitchen's website.

I hadn't paid enough attention to the pictures of his products.

I was going to say, normally there is hole size specifications and you just want to make sure you have enough side wall thickness. Often it will be like 1.5-2x the thickness of the retaining nubs, so they don't break in to the infill and have enough material left that there is still strength at the points.

Just remember these are more for repeat removability than thread strength in most cases, as often with standard infills you will tare the entire hole out of the printed body before the threads will fail even with out an insert.