First picture is a non-conductive shield for the ram, this shouldn't need to be replaced.
Second picture appears to be a heat-spreader for some sort of voltage supply, likely conditioning for the CPU or GPU. This is most likely a non-conductive material. Not really sure if it is wise to replace. (I have seen a similar material used to take heat out of an industrial PC's CPU to the chassis for passive cooling)
The third picture is most certainly the thermal pads for the two large chips (cpu and gpu I would assume). This could likely be replaced by so called thermal adhesive which I believe is somewhat permanent, but standard non-conductive thermal grease may suffice. They went to great care to place additional non-conductive film between the two chips, so you will want to make sure the heatsink proper does not come in direct contact with either.
You should probably avoid metal-based heat sink compound in a laptop, anyway.