I am probably going to have a standing-seam metal roof installed on my house and garage. It will probably be cool roof. I am pretty naive about everything except the difference between standing-seam on the one hand and "r-panels on the other.

The re-roof will include two types of construction. One is replacement of an existing shingle roof. The existing roof deck is planks, not plywood. I plan to spray-foam insulate the underside of the deck and seal the attic.

The other two roofs are flat-roofed additions. There, I plan to frame with minimal rise for the metal roofing. These areas will be sloped in different directions (right angles). One is a lower-slope continuation from one of the gabled roofs. The other will border on that and end at the gable end. The existing roofing has to be removed to eliminate the vapor barrier and that will also be spray-foam insulated before the metal panels go on.

I'd appreciate any advice that is offered. I have some specific questions. Are there different options for treating the edges of the roof? What are the choices for underlayment? This roof will be difficult to get onto safely compared to shingles and the flat roof. Is there any practical way to install attachment points for a safety harness? (I am planning on installing both photovoltaic and solar thermal. I have nearly South-facing gable on both the house and garage.)

I understand that the metal is lighter than the shingles that will be removed. The dead load will be less. Do I have to be concerned about the corresponding increase in the live load? This is Gulf of Mexico hurricane zone (New Orleans). I wonder if hurricane ties should be added at this point if it is practical.

Thanks for reading!