"tournament (such as NCV tournament chips) have to be approved by Nevada Gaming before use? Thanks again. Bedo"

You bet. Yes. Of course.
That said:
IMO, there are certain tournys that, may or may not apply to.
I do a lot of corporate tournys. The corporation puts up prizes and ONLY their employees or customers are allowed to play. They are closed to the public tournys.
The corporation pays us a fee for running the tourny. There is no buy in. We do not pay out cash.
We have an agents opinion that they are not considered gaming events. The key there is the word "Opinion."