About pathfinding, it is not perfect I am agree, and get stuck on gameobjects added by the server, but with default settings and without plugin, I am rarely stuck (of course, this depend mainly of your profile and your current zone, but if you use NPC of your profile (with path tested by the creator) you will not get problem, but if you start to use your NPC with an random profile (not optimized) you have chance to get problems).
About quests editor, it is recommended to slit your profile in several files (and at the last step load next file), but if you need to insert step, you can edit with notepad, xml codes of steps is easy to edit manually (and I think than you don't need to insert a step near the firsts frequently).