It won't use that much charge compared to just driving around - we use so much power moving a multi-ton vehicle at highway speeds it's insane.

If you are lucky enough to have a vehicle that has a heat pump and not just a resistive heater and you use it just enough to stave off the cold, you are probably going to be in a very good shape. If you happen to have a vehicle with seat warmers, even better - heating oneself is better than heating the cabin air. ICE also have those, but you'll have to be sure to run the alternator from time to time, generally EVs will figure out when to charge the 12v system from the traction battery.

Will an EV like that outlast an ICE car? Based on the figures I'm seeing from a brief search(around 30 hours with a full tank of fuel), I think it's likely, on average. But there are too many variables.

You are completely right about the CO emissions. Can leave the heater running without worrying about poisoning.

Depends on how the heat is produced and how comfortable you want to make it, but in round numbers I would expect heating the car in a snowstorm to eat up about half the battery capacity every 24 hours. I still keep emergency blankets and I would run the heater as little as possible.

I am getting very much the opposite impression from various recent newsarticles in Sweden, where EVs are common and traffic jams due to snow, accidents etc. are commonplace as well.

Google translated a recent P4 article:

The snow weather over southern and western Sweden has had a major impact on traffic and people have been sitting in traffic jams for several hours*, reports P4 Gothenburg.

A major problem has also been electric cars abandoned on the E6 by their drivers. The battery runs out when there is so much heat in the car.

- We will be able to salvage(tow) a lot of electric cars that were on the E6 during the night, says the Swedish Transport Administration's road traffic manager Mikael Salo and believes that this is one of the shortcomings with the new cars.