For the graph comparing the search depth and the run time should we have a graph for each heuristic that we created or just our best/worst heuristic?
No, you should use only one heuristic and do it for the MinMax only. You will be comparing the run time for the first move with for the different depth limit and create a graph out of it. You could use the provided heuristic if you want.
I did an analysis of my best one for my assignment.
To add on to this question... are we looking at both ExpectiMax and MiniMax for the graph? Or would both of those take the same amount of time to search?