I just skimmed over the responsives and maybe someone commented already. I didn't see any ice dams in your pictures. At least anything caused by escaping heat. When the air temperature is near freezing and you have two feet of snow insulating the roof there's going to be a little melting no matter how well insulated. The question is how often. Once every five years or once a day. Rot needs a lot of soakings. Vapor barrior faults cause water stains on your ceiling.