For the grouping material properties it could go like this.

A single object has the color box enabled. If you group two objects then the color box has an X on the color box as default and keeps the childrens color boxes upon grouping. If you want to color all objects in the group then you must select the X'd out group material box, assign material, then the material is carried over to the children as well. If you then want to have one child different then go to it's material box and change it.

I'm really glad we're thwoing ideas around about about the interface, hopefully it can sprout some new ideas about what everyone like from other apps.