just not sure what the shell is really even for. happens when i use other shells to like dicktator
I haven't used the product you're referring to, but the general purpose of a geoshell is to provide an additional surface that's just microscopically above the surface of the figure in question, and which follows the contours of the underlying figure exactly. That way, when you apply a texture to the geoshell, it essentially acts as an "overlay" on top of the existing figure's base texture. Of course, the textures you apply to the geoshell are usually transparent in places that you want to see the underlying figure, or else you hide those portions of the geoshell. (If the geoshell isn't transparent, you end up with the "looks like it's made out of white plaster" effect that you're seeing.)
So, it's possible that the product requires a two-step process - the first step being applying the geoshell (for which you may have to have the main figure selected) and then a second step where you apply a texture, for which you may have to select the geoshell, rather than to the main figure.
FYI, one of the other technologies for doing overlays in Daz is the "Layered Image Editor", which essentially allows you to stack multiple images together on the base texture itself, and have Daz merge them together at runtime. Some vendors take an LIE approach to things like makeup, scars and "other materials," while others use the geoshell approach. Kind of a matter of personal preference on their part.