1. Server 49, Castle lvl 27
4. I think the idea that the Kings(i would imagine all of them, since it a server merge and not a kingdom one?) agree on the server to merge with, if you let people just freely jump around thats not gonna do any good, the kings represent their kingdoms and are,most of the time, the people with the best overview(Obviously i AM king and my opinion might be biased). For the mechanic on how to merge i prefer, under the condition that its not set in stone at that time already, to wait for the official strategie since people wont be able to agree on anything and get a good discussion rolling without it beeing official first.
5. difference in sever lifetime, this game is about beeing efficient to get ahead, doesnt seem fun to me to play efficient, be one of the better guys on your server, merge with a 1 week older server, and dont have any impact anymore. If you just merge server without managing the difference in server lifetime i would rather have you not merge them at all. You could as example speed up one of the server to get him on the time lvl of the other one, so basically giving the newer server the time difference in buildingspeed x2(for research, would have to make sure that its spend 50/50 on buildings /research)give us a REALLY big shop including all the items you might have bought in that time, and a reasonable amount of ressources(maybe give us the average ressources you got per day of your last 2 week per day or something like that). the same average thing you could do with the hero xp. Last but not least we should get all of the quest reward we could have gotten in that time. Maybe look at the average of quests each player did in a certain time(i dont know if and how that would be technically possible). anyways, this is just to show that it might work, the idea is in no way something that i would recommend to do exactly like i mentioned.
Eddit: Obviously it would be WAY easier to let the older server stagnate until the point that he has the same server lifetime, that would mean that one server had to wait a lot though.