Your quest issue sounds like you may have an issue with the quest file for that particular NPC. Maybe check the script for anything bad or just rename it for now to see if it stops the errors.
As for getting the load spread across multiple servers, good luck :P I tried that a long time ago and found that the port assignment from the launcher is horrible. It doesn't keep track of which ports are supposed to be used on which launcher. So, if a zone crashes and restarts, it may restart on the wrong zone server. Which means that if you have them both on the same network, the ports won't be forwarded to the right server and people won't be able to get into that zone. And, if you are considering running all static zones, that is even more of a nightmare when trying to split them between multiple zone servers. It is almost certain to have randomly locked out zones as a result of issues. The only way you can run multiple zone servers currently without issues would be if they were on completely separate networks with separate internet connections. Because, then you can forward the same port ranges for zones to both servers and not have to worry about the poor port assignment, because it wouldn't matter anymore.
Here is my old thread about it:
http://www.eqemulator.net/forums/showthread.php?t=25052
It probably wouldn't be a bad idea to get this fixed. I may know enough ab out code now to actually fix it myself, but I just don't have the time to look into it right now. I will add it to my list of things to eventually check into, but I wouldn't hold your breath :P