My plan is to use Huber/Advantech Zip R sheathing with 1 and 1/2 inch rigid foam (2 inch total) with 2×6  on 16 inch centers.  Then attach Delta dry and Stucco lath, then three course stucco.  

Questions:

1.  How is the best way to attach the Dorken Delta material to the Zip R sheathing?    (Fasteners?,into Studs?, how much penetration into stud) 

2.  My Architect is concerned with the weight of the Stucco on the structure, especially since the lath will be attached thru the 2 inch Zip then into studs.  His concern is the cantilever or extended stucco layer so far from the 2×6 studs the stucco will have significant cracks due to the weight of stucco over time. 

Your expert help is greatly appreciated.