Sorry for not getting back to this sooner but I generally use the foam for the forms / edges & leave it in place - To finish it off we either use a spray on water proofing material which can be painted, or run hardi board & finish off with stucco, paint, etc... mind you we don't do many as we primarily focus on remodels, (and most houses are on crawls or basements in this area) but that is what we have done on the past.
Sorry I don't have any detail drawings handy, but as I recall GBA or BSC has had some good ones & other available options.
I am a builder of energy efficient homes in Montana. Western Montana is about 7700 heat degree days and we typically do not need air conditioning due to night time heat loss to the sky. It is a dry climate, too. Right now I can see a big tall column of smoke in the Saphire mountains from a forest fire.
I have been cutting off one side of my insulated concrete forms to allow the slab to overlap the icf stem wall. We have frozen ground in the winter so frost level is about three feet down, where we park our footings. By removing the foam from inside the icf stem wall, it changes the r value from 22 to 10. Many of these slabs are heated with radiant tubing so an even greater heat loss can happen. Most builders here are doing crawl spaces and do not have a clue how to construct a slab for a home properly, let alone a crawl space. To do a crawl space right, it is a hell of a lot of work. I favor slabs because of several factors. I don't care if they get rained on , they do not squeek when steped on, do not rot, can be chem stained, can be a heater via radiant pex, and have lots of thermal mass. So I do stem walls three feet down and spend money backfilling and insulating my slabs.
Several good builders here are now building the walls of their homes thicker. Some are ten inches to twelve inches thick. Because of the thicker walls now we can fit more foam on the slabs' perimeter and still get the load berring to work. I did one wall 22" thick and was able to get a slab perrimiter R of 40 with ten inches of the eps foam. This was a double 2x4 wall and the load transfers down the outer 2 by wall.
To protect the foam, I use steel coil stock in whatever color the homeowner likes. We screw this to the plastic ties of the ICF wall. I have used synthetic stucco over a cement stucco brown coat, but that was a lot of work. Some builders use a vinyl soffit product here. Others use fiber cement siding products. I have two homes, a kind of his and hers life style. The main house is a slab and the cottage is a crawl space. The main house has the advantage of thermal mass and I see this work durring certain weather conditions. In the fall the slab will hold the days heat while my cottage is colder. And I have three feet of cellulose insulation in the attic of the cottage. When I came home today from work to the cottage, it was 80f out side and 67f inside. We think 80f is hot in Montana. Thanks!