Since you like listening to music at low volumes, have you considered headphones instead of loudspeakers?

I recently got a pair of Wharfedal Linton Heritage speakers with stands to replace Focal Aria 926 speakers. They are powered with PS Audio components; Stellar Gain Cell Pre-amp/DAC + S300 power amp.

I cannot answer all your questions but I will comment where I have a valid experience of my own.

1. Character:
IMO the Lintons don't color the music and I find them to be excellent with Classical and Jazz. Vocals and acoustical instruments are also very well presented.

3. Low volume:
I also do a lot of low volume listening. They are great for this. You get the feeling for the music and are drawn in, even at low volumes.

4. Small room
My room is around 28m2 and it works very well. I can turn them up quite high before it gets to be too much.

5. Other speakers: Focal
I experienced eaxactly what you describe with my Focals. When I read about the "BBC Sound", it sounded like that would be more to my taste. So I went to look for speakers in that style... The Lintons bring what is missing with the Focals. (I am not saying Focal is bad, IMO the Aria 926 are just a different style: More analytical - Less musical).

6. Other speakers in $ 1500-2000)
I auditioned Harbeth Compact 7-es3 / Spendor Classic 2/3 / Graham Audio Chartwell LS6f and the Wharfedales. They all sounded great (more of less similar to the Wharfedales) but they cost 2-4 times as much.

Conclusion: I recommend the Wharfedale Lintons without hesitation. I think you will be hard pressed to find a better performing speaker in that price range.

Best of luck.