I think you are correct. The two bags by the metal box do not even look like they were moved, let alone exploded. The metal box has not even been dented. This was mainly to hurt the poor people in the crowd.
I would agree that the position of the barricade looks like the bomb was directly behind it, but that bag could still be the bomb being placed in position. I strongly suggest that authorities track down the person with the white shirt and brown jacket if he/she isn’t a casualty.
Correct. Sounds like this was a pressure driven device simply designed to move shrapnel. Would not have caused major structural damage. Could be a lot of holes in everything though from the shrapnel that we cannot discern in this image.