I love your fei yen!
Miracle blend has its own primer, but I’ve heard of some people who varnish first.
There’s no need to add tinner, the air dry paints are thinned by water.
Not sure what kind of “thinner” you mean but just to clarify the thinners that are used with Genesis are not compatible to air dry paints.
The Che’air acrylic paints do have thinner. I would really like to know what it is…