Um... no, it doesn’t and no, most US bombs and projectiles do not contain depleted uranium. DU is not an explosive or an explosive enhancer.
That is correct. Because of the very large blast radius and the damage mechanism, having shrapnel would decrease the effectiveness of the MOAB. This bomb is designed with an unusually thin and light aluminum skin, so thin that the MOAB needs a pallet for support during storage and transport, so that almost all the explosive energy will go to and stay in the shock wave.