I live in zone 7, western Wyoming. I am insulating my addition using 5″ of cellulose, plywood, and 3″ of polyisoncyanurate. I have 2 questions.

1) I have little to no knowledge about cellulose. Where can I find information on which type, blown-in, damp spray, or dense packed cellulose I should use, and what are the advantages and disadvantages of each given my cold climate?

2) I spoke with my contractor about using 3″ of polyiso as an exterior insulation, and he is unfamiliar with how to work with the added thickness of the polyiso. Are there any blogs or articles you can refer me to for how to affix additional layers of external insulation?