D+7: I ignored Switzerland for the same reason I ignored Australia. (I have insufficient info and know it) But yeah, between the Alps and the guns it looks probable to have a Swiss community.
D+30: Seriously lacking info on this one, but the hints in cannon look like the first month will be less of a "mega-death" event and more of a "mega-coma" event. 2 weeks extended incubation with weeks of sick/coma times means that a mere 4 weeks in there won't be all THAT many corpses yet. Prepping for burial is a LOT quicker when embalming is simply not an option due to the state of the body. So yeah, both lack of personal and lack of "good looking bodies" is gonna cut WAY back on traditional casket burials. Backhoes make digging graves, even in winter, somewhat trivial. Enough that mass cremations or mass graves are probably not a thing yet. (Or not officially a thing yet, crematoriums have been known to double up on bodies when funds get tight (or lazy))
If local terrain is particularly rocky or REALLY frozen then bodies traditionally get stored instead of buried immediately. Plans will be started on how to bury all the bodies come spring. (And then the troll make that a moot point)
D+60: Doctors and Nurses would be the first sick remember? Only the immune or fully quarantined are still up and about. And while they might not be armed - they are beyond overwhelmed and recruiting any able-bodied they can as helpers. Those helpers are civilian immune/walking sick and National Guard/Army/Marines...Cops... And yeah - the soldiers probably WOULD be armed because the guns are an official part of the uniform. (Unless they are the lucky few in a quarantine suit of course - hard to use a gun in those) The civilians would definitely be armed. They wouldn't stop a gun carry habit just because of an epidemic. (Ok, the unarmed civilians wouldn't collect guns just because of an epidemic either) Er... local gun carry laws are really, really mixed tho. Too many state law variations (plus climate) to cover in a broad guess like this one. I'd research the local specifics for cities I set a story in.
You are also forgetting just how "impossible" those Rash comas are. By now its month two. Many of bodies have been without food or water for up to 6 weeks. And they really, really don't look human anymore. They look like fungus growing on a corpse. Once the first trolls get up and start EATING people... I'd predict it would be really easy to get the remaining doctors to pronounce death on the remaining Rash comas.
I'm also assuming the delay in infections will correlate to a delay in troll hatching. Internet and phones are still a thing by then. And relatives are quite widely spread - so video reports WILL get sent. The ones that believe the reports and start killing/burning the bodies ahead of troll hatchings will survive better. If the troll hatching correlates to weather instead... we probably had trolls in Florida by week 4. Although the sooner the troll reports are believed and acted on - the better the overall survival rate. So I went with a two month delay.
Y1 - Trolls are wide spread enough that gun carry is VERY common now. Although the comic is now hinting that the "ghosts" were more of a problem then the trolls. Apparently guns don't work on ghost either. Not sure how much mages are required because Sweden seems to do fine without them.
Y10 - Yeah I considered the climate. Did I forget to specify that the South and Eastern Seaboard is abandoned? (Individual islands, especially northern ones, may still be inhabited) Those 9 million survivors are gathered in just a few dozen cities. Ten years in and the small shelters are probably all evacuated or the nuclease of a larger town. And I predicted the nuclear power plants would be in use for at LEAST as long as it took to do a safe shutdown. Depending on the design that time frame in USA seems to measured in "months". So by Y10 all the nuclear reactors they have still going have a stable resupply of fuel and spare parts. Might have newer (and safer) reactors going. WILL have a combination of hydro-electric, solar, wind and coal power up. Also diesel generators.
POPULATION DROP SHOCK
Um.. google does not recognize that term. All I got was discussions on global fertility rates. Quite useful for looking at Iceland's population drop. After all, they didn't get The Rash. And the troll/ghost impact seems fairly minimal. So it seems Iceland suffered from a massive fertility drop more then a high death rate.
The most useful source I found for human's response to catastrophic death rates was actually the website for the Voluntary Human Extinction Movement.
http://www.vhemt.org/death.htm I didn't assume The Rash was a measly 0.01% death. Not even the 10% die off you claim. My theory had 97% of Americans dead in a YEAR. That is catastrophic. America is beyond broken. The survivors will pick up the pieces and put them back together in a new configuration they will then CALL America - but it won't be the same thing. I looked to how emigrant societies recover for ideas.
Will international trade be borked to heck and gone? Yes. Yes it will. Will that lack of... all the trade things... impact industry in USA? Um... YEP! There will be many, many things we suddenly need to adjust how we make. Or simply do without. But North America is unique in that we have just about every raw resource on the planet already here. Food, wood, oil, metal, sand.. Even the rare earth metals! (We just don't dig them out much 'cus its cheaper to import) The Google Archives are in Nebraska. Lots of other archives in Universities and private archives, don't think information will get lost. The majority of industrial manufacturing is in the Midwest Heartland. (Aka the bit with really cold winters and right by the food) We have an extensive river/road/rail transportation network. And the one positive side to the quick die-off is that we will have spare parts out the wazzoo! Critical spare parts will go first of course - but we might not run out of staples or paper-clips for a hundred years or more!
Catastrophic death rates result in baby booms. Also in massive innovations and sociatial changes, so any story probably will completely miss the major changes history records. Anyone predict the Civil rights movement after WWII? Or women moving into previously male-dominated jobs? But I don't think humans are mere remenents in America tho.
Radio: Yeah my theory is pretty weak on the radio explanation. Perhaps new technology in radio tuning means Scandinavia's outdated equipment tends to pick up multiple stations at once? Perhaps a new Maunder Minimum means those international stations come in best in dusk and dawn? Maybe its the "ghosts" and my theory completely fails to account for those? (Seriously, I have no idea how the ghosts affect things)