Effective Texturing 3D items for DAZ Studio in ZBrush - how to?

wargis

Hello to all! I have a question about Zbrush way of texturing various items, especially clothing, to generate accurate displacement and normal maps. For a start I attempted to make a custom texture for Mall Girl Shorts for Genesis and the main base texture was painted in Photoshop. Looks like this (Texture converted to Polypaint)

Then I wanted to add colored 3d stitches onto pockets,belt loops and other places, using free IMM Stitch brushes, and then add decorative elements like embroidery via Spotlight. But when I attempted to colorize this stitch brush via Gradient and Switch Color panels, I get nothing for stitches, they remain uncolored, and when I want to paint stitches over the surface of the subdivided mesh, I need to Freeze Subdivs and then all Polypaint texture disappears (becomes blurry). Is it possible to colorize stitches in, say, brown and then export diffuse, displacement and normal maps, joining this base primary texture and colored or displaced stitch lines? I don't want to change the initial geometry of the mesh, I just want to get the Displacement Map, precisely corresponding to the diffuse one.
The same concerns decorative elements like pockets and embroidery, which can be added via Spotlight - how to save all this elements together with the primary texture on all maps? I have seen so many beautiful items (especially in Mec4d store), obviously textured in Zbrush and I feel it's rather simple but I don't know the right workflow. Can I export the Diffuse texture as PSD to keep all its elements on separate layers and the displacement texture as a whole? Which options are better for exporting textures from Zbrush?