I think the question number 1 is high on the wishlist no? For me too
But if youre talking about Z - mapper in Zbrush I have yet not seen any specific setting for XSI, You could go for standard Z- mapper settings with following in mind:
Tangent normal map for animated objects(obj that deforms and change shape) and object space normal map for static scene objects.
Be sure to assign the right texture cord(for ex explicit UVVs). in the normal map node. Sometimes the normalmap effect doesent show in the render up until I do that.
In my experiences these problems uccourrs: Dont use normalmap with to much geometrychanges. Its more like an advanced bumpmap. Especially polygons that crosses each other is no good. And pinching in Z - brush wont work, just standard draw mode push in and out of polygons.
You could combine a displacement map with low subdivision level and use a normal map for details, instead of just using displacements and waiting forever to render.
But if youre going for games that might not be such a good idea…
Anyway hope someone more experienced in this matter will jump in…