How do I access the pathfinding behavior cell array?

I've been trying to set up path finding using the built in path finding behavior. This has been extremely frustrating, as the official documentation is incomplete, and the path finding example file uses a workaround. Where can I find a complete list of expressions that this behavior uses? The manuals list was missing most of what I need. How do I see the array that it uses? How do I refer to specific cells, by their number, without using some weird inefficient workaround like generating another grid on top of it or creating a new array just to keep track of the original? How do I change these cells obstacle status? How do I see which cells, (not nodes) the pathfinding object will be moving through or moving to next? How can I find out what numbers to use for the path finding condition "is cell obstacle" when the cell being tested by this condition needs to change in real time?

As far as I know the expressions in the manual are all the expressions you can use inside your events/actions.

Let me ask a different question -

How do you determine what cell that an object using the pathfinding behavior will move through next? (cell coordinates not layout coordinates)