The area under elevated lines is unusable only if you make it that way. Tokyo is great at using space below bridges and elevated lines: https://images.app.goo.gl/zpq5T3m5FPSr4eoN6.
Yes and Chicago's stock is super old. The Orange Line is newer and is also much quieter and smoother. New rail in America, elevated, can be pretty quite and enjoyable. I like living near trains personally. It's relaxing to watch them go by in the evening, while sipping on some whiskey or wine.
Your mind will eventually tune out the noise of a track. Our house was near a freight rail track that had a run all night. Never woke up after the first couple of days.
This is the first time I've ever heard of Metra referred to as "light rail". Metra uses enormous diesel locomotives and runs on freight rail ROW (for the most part)--there's nothing "light" about it.
To be fair, most European commuter rail does the same thing. They just use electric heaters, so it doesn't look like their tracks are on fire. Chicago was built up with a big natural gas infrastructure for some reason (like every home seems to have gas heat/dryers) so I guess it made sense to put gas heaters on the rails.
As to weather, Chicago has tons of it and manages fine: https://chicago.curbed.com/2019/1/31/18204627/chicago-cold-w...