I notice that a lot of pictures on zbrush have lots of texture, but I’ve never seen animation with that kind of texture. When I see animation from maya or wherever, it always looks smooth, and it doesn’t have the same detailed look. Is there a way around this (if this is the case)?
I don’t understand 3d animation. If it needs to “render” to have any type of texture, then what is the point of using zbrush to make texture for animation programs?
No external animation program can effectively animate a mesh with the number of polygons Zbrush works with. Most couldnt even open the models.
That is why these details are exported from zbrush as a texture, and applied to lower res geometry in other programs as a normal or displacement map. You see this evidence of this in next generation games, where the characters sport more detail than their polygons could support (normal maps), and highly realistic CG creatures in movies (think more Davy Jones from POTC2, not Pixar 
(Displacement).
The point is, it gives the mesh the appearance of having many more subtle details than the relatively low level of polygons could ever support, without actually having the performance burden of a model with millions and millions of polygons.