Eddie:
Sheetrock goes right over the foam. Demilec says no vapor barrier needed in this area. The wall is 1/2" foam board on the outside with a breathable Tyvek-like membrane on it, and all the joints are taped. Under that is OSB, then the foam.
This is an open cell foam with an R-value of 3.84 per inch, but its not the R value that is the value of this foam, but other factors: 1) The 3.84 per inch is real world R value at any temperature (other products achieve their rated R values only in the lab under perfect conditions), 2) The foam stops pretty much all air flow, fits the contours of every irregular space such as around outlets, between narrow stud openings, etc. 3) the foam seals cracks and openings where wires and pipes go. 4) the foam does not settle or decline in insulation value over time.
I hope it is really as good as what I've read. The closed cell foams acheive as much as R7 per inch, but are much more expensive and aren't as flexible and might pull loose from the studs as the temperture changes, introducing cracks in the envelope. Local contractors that use that stuff deny this, and I don't know what the real story is, but I couldn't afford it anyway.
Looks like sheetrockers will be here this week and hopefully the bricklayers too.