Hi and welcome AgencySek.

Mixing clear with textured spray paint: Do you mean spray your matte clear, and then spray the textured spray paint? Or combine them in the same can? Either way I'm not sure, but I suggest you trial it on scrap wood first.

Necessity of clear coats: Not all paint finishes have a top clear coat! I would think that with No clear coats the paint surface would be more prone to scratches and damage. Also, not sure how well oil/dirt marks from general use would clean off! Try it on scrap wood also.