You don't need to worry about the pods getting stuck in the sponge this will actually be a great place for them to breed. And I would go with live rock as well. As far as feeding the pods you shouldn't have to. I don't know the specific species DT's sells but I would guess they are either Tigriopus or Tisbe and they will both do fine on stuff that settles in the tank and fuge. And your macro looks to be like a Gracilaria species to me.