You’re right about the fire resistance—having a metal roof in the PNW just feels safer with all the trees and wet weather. I had similar noise worries before mine went on (standing seam, too). Ended up going with a thicker underlayment, plus they put battens between the roof and the sheathing. That seems to help a lot with sound. When it rains hard, it’s more of a gentle tapping than anything crazy loud. My neighbor’s older barn, though, is a different story…that thing sounds like someone’s throwing gravel at it every time there’s a downpour.
On solar panels: I haven’t pulled the trigger yet but did some homework last year. From what I gathered, most insurance companies just want to know you’re using licensed installers and sticking to code—didn’t seem like a big premium jump in my case. The electrical inspector did mention making sure all the mounting brackets are properly bonded because of the metal roof, so that’s something to double-check if you move forward. Definitely worth asking your installer how they handle it so you don’t get any surprises later.