They may in their production -- but you don't want to grind ones after they have gotten dull in use.
They can -- if you *first* undercut the steel with standard grinding wheels, so the diamond won't touch the steel. The brazing is no problem to the diamond, just steel or iron. It would help to have fixtures to prevent the angle shifting which might allow the steel to touch the diamond wheel.
Not well. You get poor edges with green wheels on carbide, and green wheels are too soft to work well on mild steels.
To make a good sharp edge on the carbide -- either the brazed carbide inserts, or as a manufacturing step in the production of the replaceable carbide inserts.
Listen to Harold -- this is his primary field.
Enjoy, DoN.