I'm confused.... I was always under the impression you wanted absolute jet black spore prints. Correct me if I'm wrong, which I clearly am. But why have I always read that they should be black....
Its very possible, but as far as I know there is no predictive test for psilocin(psilocybin). Not much other than lab-maintained testing and, well, eating them.
That depends on the strain, some go indigo if you just look at them hard. Some you have to crush but I don't know if there are any autodigesting halucinogenic mushrooms. Careful, some of the coprinous, when combined with alcohol will make you sick.