Quantum consciousness...

[I_am_not_mafia]

2

) Why should this functionality be provided at the quantum level rather than at the level of a network of neurons?

I don't think anybody can answer that until we can understand how/why a conscious observation can affect the outcome of quantum experiments.  eg: wave collapse.
Our underlying reality is obviously a lot weirder than the way our mind constructs it in our heads. Understanding how this shit works was not as high an evolutionary pressure as was running away from a bear.

You can answer it by saying that there is no need for any quantum effects for consciousness to occur.

Or to turn the question around, is there any reason to think that we need quantum effects for consciousness?