How many coats of emulsion should I put on my screen?

Without sounding like a wise guy my answer is: As many as you need. Generally speaking you should coat at least one coat on each side of the screen to achieve a minimal coating. The last coating should be done on the squeegee side so that the coating trough pushes the emulsion to the print side of the screen. The stencil thickness consists of the mesh and the emulsion. Typically, the heavier the ink deposit the coarser the mesh has to be. Another thing to remember is that the coarser the mesh is the thicker the emulsion needs to be. A thin emulsion will not adequately bridge the mesh. One other thing, higher solids will coat thicker. This means less coats to achieve the stencil thickness you desire.