Regarding the graveyard moves, how the system works is as follows: inactive accounts go to the graveyard at the end of the merge. Active accounts end up in a random target from the listed ones for the specific group.
The reality showed something different though, we do have a few accounts that were active and ended up in the graveyard after all, not all actives, but definitely some did in every merge we did so far- it could have something to do with the space left in the target servers at the end of the merge- it is being monitored. The good thing is that this has an easy solution, either the player moves the account to an active server or through support we can help and move into a target manually. The best part of this is that so far in all merges we had we didn't really have cases where an account was not found at the end, either we can help or our devs can, but no major issues have happened through these moves.
Something also important to know is that the alliances get deleted and they have to be created again in the target, the alliance class is lost and you have to wait for the cooldown to select an alliance class in the new target/new alliance. It is not ideal and was not super bad before the alliances class update, but now it is and you need to keep it in mind.