If I remember correctly there is an option to not go into the Yukon, or at least not get off the train, thus avoiding Canadian Immigration. We did this one years ago, perhaps it's still offered?
The standard balcony suite are lovely. Avoid extreme aft suites if you can due to vibration. Great theatre, great aft lounge, with balcony. Small, intimate ship, cozy at times if weather is bad. A bit bouncy in heavy seas.
I'm not a single but we've befriended singles in the past. No need to just stick with other solo travelers. Trivia, excursions and shared tables are good for facilitating mingling. Many couples are not joined at the hip.
That's disappointing, don't remember this in the past. As for CR, there's no excuse for bad acoustic architecture--this should be integral to the design from the get-go.