I'd check that the normals are facing the right way. A good way to check is to select everything and set all surfaces to single-sided ('1S' button on the AC3D control panel). If anything disappears, the normals need flipping (in 1S, the surface can only be viewed from one direction).
If you can post an image/s of the problems, we should be able to help more.
You can easily add as much detail as you like to a model (have a look through the AC3D Gallery) - it just takes time
