Code:
Once they are moving, I'll have a baseline to work off of that I can upgrade to include pathing (i.e. walls, dungeons, trees, terrain features). Let's take this in stages shall we?
You'd better start to think how you ll implement the zone geography before thinking how to make mobs moving. Once done, you'll realize that choosing randoming a heading will lead you nowhere.
Honestly, the pathing grid available for npcs will be far more efficient that any pseudo AI code of that kind.