In the first pic I posted, you can clearly see the OEM Yakima racks under the tent. As for the weight limit, you can decide how you want to handle it, but on the OEM roof racks, I've personally transported (one at a time):
-a 300lb Sears Professional cabinet (I have pics) on 2 separate occasions
-a 300+ lb sofa
-myself and my g/f at the time sat on them simultaneously (300+lbs combined) to watch various racing events.