The first question is irrelevant and affects nothing - the same owner proves ownership of both at the outset, if they choose to let the legacy version expire, w

The first question is irrelevant and affects nothing - the same owner proves ownership of both at the outset, if they choose to let the legacy version expire, well they chose that - so who cares what happens to it? I suppose it could be configurable at purchase to allow it to be a recurring verification, if that was desired, but it would seem to overcomplicate for no reason. "Subscribing" to domains each year is legacy inefficiency. I'm not sure what you mean about DNS, any chain-based system would be... chain-based, and therefore cryptographically-assured that a domain points where the owner chooses. "Not your keys, not your domain" applies.