Well... The obstacle avoidance could be done using a 2d map (like the ones from showeq) basically showing a line where there is an impassable obstacle at ground level... but also, the obstacle avoidance is really not even needed... as long as you use the actual walk/run function of the game, if they walk into a wall, they walk into a wall
the mobs in the real eq don't do a good job of this anyway, and besides... if it is following you closely, it shouldn't get stuck badly anyway... The obstacle avoidance thing would be something to work on for the long run, but even without that the above should work for what is needed for now... providing follow routines (for players, and good mob chasing routines) and providing the waypoint scripting for wandering mobs...
anyway it would still be more complicated than the above, that was just a basic overview of what could be done... I need to hear back from the dev team to see if it is feasable...