I have to vote against the expanding vision, that basically requires us to make our structure thicker, and as such will use Craptons of energy and give us little in return. We should upgrade our vision next time we undergo metamorphosis, however. The pondering High Integrity matter is probably pointless but consumes no resources, so we might as well.
It is assimilation, it has a significantly better energy use to energy production ration than producing crystal to surround the high integrity matter. It will also help to locate any better mineral stores. The argument that it drains a great deal of energy and produces little is, at best, overstated. Metamorphosis is probably impossible until we assimilate a new form of material, so scouting(and increasing vision is about sprouting tendrils off of our side, not just growing everything by 5 layers) is necessary if you want to speculates on such things...
Also, there is no reason to believe that mental activity does not consume energy, in fact, what we do know, is that concentrating enough to go into tick mode actually inhibits energy generations, so it is in fact the single most expensive thing that we could possibly do... Although there are no known time pressures so voting it down would only serve to inhibit turn skipping, which there is no reason to do.