Ice, snow and moisture on a new Standing Seam roof

Hello, I am the owner of a new home in the central Ohio area with a standing seam metal roof. The roof is the old-style standing seam, fabricated from 2’ galvanized panels on-site. Our house is approximately 1 ½ years old. As with many people in the Midwest and east, we have experienced a particularly bad winter. We recently received at least 16” of snow and are having some problems with snow and ice buildup on some our roof sections. Here is some information about our roof: 1) Most roof sections are 8/12 pitch. We have two roof sections on the front of the house that are a little over 4/12 and one small section on the back that is 5/12. 2) The 4/12 sections are built with 2x12 rafters, ½” OSB for sheathing and approximately 8-10” of blown in insulation in the attic. All other roof sections (except the garage) have 6” Structural Insulated Panels for the roof, with no attic space or venting (timberframe construction on the inside of the house with high cathedral ceilings). 3) 30# tar paper was applied to the entire roof before installing the metal. Adhesive snow/ice dam heavy tar paper was applied in the valleys. 4) Venting is minimal. Both 4/12 sections have venting in the soffit (although batting was stuffed near the soffit). One of the 4/12 sections (I will refer to this later as Roof Section A) is interconnected with the garage attic. The garage attic has large gable vents in both ends. Now here are my problems: 1) With the heavy snow we received, both of the 4/12 sections (Roof Section A included) were holding a large amount of snow and (what turned into) a large amount of ice. This is mostly attributed to the 5” gutters that were installed, I believe. The gutters were holding back a tremendous amount of snow and ice. Large icicles formed. Part of one of the gutters got all twisted when the ice let go. 2) I went into the attic of Roof Section A to check for ice dams in the attic and luckily didn’t find any. I did find, however, evidence of mildew/white mold starting to form between the top surface of some 2/12 rafters and the underside of the ½” OSB sheathing. The rafters felt damp at that location as well. I also noticed a small section of OSB that was wet (I think from a leak) at the peak of one valley. Now here are my questions: 1) Will snow guards help solve my problems with the gutters? Should I consider installing snow guards everywhere on the roof to prevent my gutters from being mangled? Or will this create other risks for me such as ice dams. 2) Did my contractor install the proper barrier between the metal roof and the sheathing? I trusted that he did at the time and didn’t have time to research it, but now I’m beginning to wonder. 3) I’m not comfortable with the venting that we have, and I never really was during construction. Do you think this might be causing our mildew/mold problems? If so, what are my options at this point to correct this? Thanks so much for your time and help. Jason