Well, that’s quite a long post, which means that to do the topic justice would require just as long replies, unfortunately I will only be able to address some of your points.

Firstly, in my humble opinion, free will is illusory at a fundamental level, but because we cannot with any certainty model accurately human behaviour, the concept is and will continue to be useful as a working hypothesis, what do I mean by this?

We know that all decisions are actually made before they are presented to the conscious part of the mind, you are somewhat aware of this because you do not know by introspection how any particular thought is formed, why think of one thing and not the other? Why did you choose a particular word or phrase and not some other? So conscious thought appears to be a rationalisation of preformed cognitive processes, however even if we established the exact mechanism involved and it was found that all were deterministic, it would be unlikely that a model could be developed that would simulate behaviour to a precision where prediction would be anything other than probabilistic.

There would be many variables, initial conditions required for accurate simulation would be extremely difficult to acquire with any certainty, in short, free will is simply a convenient concept, and it appears to describe what is happening, even though it might not be an accurate description of reality.

“neuroscience and psychology - seems to "reduce" us to electrical signals in a dense net of neurons.”

Indeed, and if one were to carefully remove chunks of these dense nets of neurons, one will witness the self gradually become extinct, which is why dementia is so feared by many, but that relates to the nature of sentience itself, the self is only a small part of the whole, most of which is entirely hidden from us, at least on a conscious level.