1. I was on a flight a few days ago. Two days before departure, EF showed Y9 B9 H9 ... When I boarded, it was almost full. In my section, only the seat next to mine was vacant. At a glance, I did not notice any vacant seat elsewhere.

2. It is possible, but I doubt how much they can/will do even if the flight is not full. Perhaps you can request that a few days before departure or do on-line check-in 48 hours ahead. In the flight I mentioned above, there were two ladies in 37A and 37C traveling together, and CX put a person in 37B.