I have a question on Quest setup.

When a new area is reveal, do OL put all the pits and rubbles?

Or do OL just put rubbles?

Or OL do not put pits and rubbles as they are activated when the hero step on the space?

multikiller said:

Everything in the area is revealed

That is correct.

The pits and rubble tokens on the map are not "traps", they are simply pieces of rock and holes in the floor that have accumulated over hundreds of years of non-cave-maintanence.

The only traps that will hit the heroes will come from your Overlord hand, or are specifically outlined in that particular quest.