Hube2 on "Limiting Category Depth of Page"

I'm in the process of creating a custom post type for a client project. This custom post type will have a custom taxonomy that will be hierarchical.

What I would really like to be able to do is limit 2 things.

The first is that I would like to limit the depth that the taxonomy can be created so that there can be parent and children, but know grandchildren.

The second is that I would like to limit the addition of posts in the custom post type to the child taxonomy level only.

Can anyone give me any pointers or point me to any documentation that would allow me to do these things.

Thanks