No, I quite clearly and twice indicated that it was also unnecessary. It is irrational to posit the existence of entities that are both unnecessary and unevidenced.
I didn't think that unnecessary was of any importance, as it is only from the view point of a human, which is unfortunately limited. Fatally limited on this question, because we cannot see beyond the physical matter by which we are enthralled. Likewise with unevidenced.
It certainly isn't irrational in principle, although it may be pie in the sky, in the absence of some kind of evidence. However we do have some evidence, our personal experience of existence. This experience exists, as such the rational mind is free to question the nature of this existence. Unfortunately due to its limitations, the mind has not come up with a comprehensive explanation.
It has with the development of rational ideas (philosophy) explored the various rational possibilities of explanation and materialism is one of these, along with idealism, among others. Unfortunately as these are intellectual interpretations of the evidence, there is no measure of which is the most likely to be the case.
There is an indication due to scientific experiment that the experience of existing has a physical basis, but rationally this is little more than an explanation of the local, or immediate, phenomena of that experience. It does not provide any foundational explanation of existence at all and as such leaves materialism impotent, or at least no better an explanation than the alternatives.
No. Our current scientific knowledge makes this additional entity unnecessary, as we can alter any and all aspects of consciousness by manipulating the brain, either chemically or physically.
Yes, but this circumstance may be identical in either materialism or idealism and as we don't know which we are experiencing, we can't begin to compare the reality of each. Or that what we experience is not something else entirely.
Ruling it out is irrelevant.
Yes, this is known as unfalsifiability, and is usually a strong indicator that the hypothesis is incorrect.
This may be a useful rule of thumb in experimentation, but is impossible once we look beyond our immediate physical circumstances.