Re: Roof venting
Plumbing vent pipe into the attic.... yikes big no no explosive gas comes out that pipe.... It can be vented threw the roof likely no snow will sheer it off as a round pipe is strong and 3" diameter does not make for much resistance to the snow just moving around it.
There are codes about how far from windows to avoid fire and smell issues & codes out walls in proximity to roof soffits and again windows or doors.
Any an all of my comments are just my opinion and not to be confused with facts.