>>>>>3) How, when, and why are the inserts put in and used?

At least, here's some trick inserts that ought to confound anyone's answer!

>>>>>2) What type of material is used (I know clay) and is it specialized.

Chipology 201 teaches us that the material used in chips is a manufacturers secret but that Paul-Son used white lead powder in the process. Which is why they manufacture in Mexico.