Hi Simon, yup like Joe mentions the grouping and object organization functions are in the scene browser, the help file info is here:
http://moi3d.com/2.0/docs/moi_command_reference11.htm#scenebrowser

You can use a couple of different methods - you can either assign a name to the objects and then an entry will appear under the "Objects" section of the scene browser, or you can also assign styles to objects which will make them into different colored sets. You can also use those methods in combination if you want.

I am planning on adding some other organization methods as well but for now those can help do the kind of stuff you're asking about.

There's also a "Types" section of the scene browser that lets you target objects organized by what type they are, like "hide all curves", etc...


re: Sculpting - unfortunately freeform sculpting like ZBrush does where you just put brush strokes on your object to raise or lower small individual zones of it is not a great fit with NURBS modeling technology in genereal. NURBS models are often made up of a lot of separate surfaces stitched together, and often times the stitched areas are at "trim curves" not at the "underlying surfaces". This mechanism tends to work well for doing booleans which NURBS are focused on but not so much for doing polygon-mesh style sculpting of the objects involved. See this FAQ entry for some more description of how the "underlying surface" structure of NURBS modeling works:
http://moi3d.com/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

So mostly if the kind of stuff you're doing would benefit a lot from sculpting you should really be looking at doing the sculpting part in a separate application from MoI, like ZBrush for example. MoI is stronger with the kinds of models where much of the model is derived from 2D plan curves rather than from freeform sculpting. A lot of times certain model styles will work better using different kinds of modeling technology, there isn't really one single method that works the best for every single kind of possible 3D model since there is so much variety. Things that are more structured and mechanical will be a great fit for MoI, things that are more organic and sculpted will be a better fit in ZBrush or a sub-d modeling program and are not such a great fit for MoI.

So if the kinds of models that you need to build are highly sculpted/organic in nature (with lots of small bumpy details and stuff like that) MoI is probably just not the right tool for that particular kind of work.

- Michael