After exhausting my drive and patience I am doing a standard formed basement. I am looking at the "graywall" waterproofing and wondering if rigid insulation can be put over it on the outside of the foundation? Also, how much rigid insulation is appropriate? I was thinking of doing 2" thick sheets

If you don't have water, you don't need waterproofing. Controlling rain water from gutters and providing proper grade away from the foundation are the first defense, followed by proper tiling at the foundation. As for exterior rigid foam; 2" works in most cold climates, but knowing where you are is the first question.

I am in Chicago. zone 5. whether there is no water there today, or not, I can't imagine anyone not waterproofing their basement wall.

I don't think the below grade insulation really cares much where it is. 2" seems pretty good in Zone 5, but if I was out and exposed on the prarie, I might throw another horizontal sheet around the top 4' to provide additional insulation against cold ground temps in winter.