I think it would be a good idea to have some kind of penalty for having multiple boots. For instance, when a player reaches 10 or 15 boots and a player has marked them as an enemy they will not be able to join their games. The enemy status bans basic players from joining games but not premium players at this point.
We've discussed this in the past and my recollection was that something was put in place but maybe we just talked about it.
Nothing that I'm aware of. I can't even think of what the last functional update to the site was (something requested by players or designers), but I'm pretty sure it's been a few years.
Pretty Sure it was the "Next Turn" button.
I think it was the "Rematch" button.
It sure ruins non NvN games sometimes.