How do I make a NPC lie down on the ground like the water beggars. By lying down I mean something like http://images3.wikia.nocookie.net/__cb20081109050957/fallout/images/1/16/Micky.PNG

Under furniture place a FloorSit marker and make a UseItemAt package to get him to use it. Send me a PM if you want more help, but if someone else offers best go with them. I don't have much experience with AI.

That's the FloorSitMarker, found under World Objects --> Furniture. Several ways to set it up, but the easiest is probably to drop it in where you want, position it, and set it to a persistant reference. Then give the NPC a 'Use Item At' package, and set the specific reference to that particular sit marker.