Metal Roofing questions - restrapping and extending drip edge

Hi folks,
I'm having a roofer redo my metal roof with standing seam. It is 3 in 12 pitch and located in northeast with lots of snow. I recently refinished the attic into heated living space. Rafters are 2x8 on 16" between which I put styrofoam ridge vents and then 6" fiberglass, then drywall. Probably not enough but I didn't want to lose any headroom. There is of course some heat loss and occasional problem with ice dams.
I'm going to ask the roofer to restrap the roof to leave 3/4" or 1.5" of air space between the plywood and the metal. Probably this could be vertical strapping of 1x4 open at the lower edge and with a ridge vent at the top. From the inside out, it will be 1/2" drywall, 6" fiberglass, styro vents, 1/2" plywood, 30 tar paper, 3/4" air space, metal. I'm told it will keep roof colder and help prevent ice dams. However I don't want the metal roof to bend under weight or if I stand on it. I would also like to add more foam insulation on top of the plywood under the metal roof but since I already put venting underneath, I think it would be counter productive.
The other question I have is regarding the width of the drip edge. I would like to extend the overhang a bit without adding to rafters because rain blows onto the siding a lot. This could be done simply by changing the fascia to be 3" wide (instead of 1.5" as it is now) and extending the drip edge out 3". Is 3" too wide for a metal drip edge? I want to make sure it is rigid enough so that it won't be bent by ice or by leaning a ladder against it.
-- Jeff
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