1 cubic metre
1m2
I'm assuming you mean one meter deep with a one square meter footprint. The answer is 1*1*1=1m^3 = one cubic meter. Actually, that is how much dirt was taken out to make the hole. There should be no dirt in the hole, otherwise it wouldn't be a hole.
None. Its a hole
600mm into cubic meter
None. A hole is the absence of the material.
None. All the dirt is removed to make the hole!
None. If it's a hole, then the dirt has been removed.
125 cubic feet
none, its a hole.
None. It's a hole. The earth has already been removed. If you remove any more, it's a different size hole.
Theoretically, none. The amount of dirt excavated to create such a hole would be 1 cubic metre. However, excavated dirt (depending on the nature of the dirt) can increase in mass by up to a third the original size. That is why when you dig a big hole then fill it in (getting all the dirt back) the hole is raised on top not flat.
None. It's a HOLE.