(1) Regardless of what theories people have regarding the existence of free will, it appears as though it exists.
(2) Regardless of what theories people have regarding the existence of randomness, it appears as though it exists.
(3) There is empirical evidence that free will and randomness do exist, and there is no logical proof that free will and randomness do not exist.
Determinists think they have deduced that randomness and free will do not exist. However, those arguments are not tautologies and therefore are not conclusive, though obviously they are strong enough to persuade determinists.
The appearance of free will and randomness qualify as empirical evidence, and thus will remain open to question until they are observed to be false (e.g. the apparent random events are explained deterministically). They can never be proven (in the mathematical sense) to exist.
Almost all meaningful knowledge of the world is evidence-dependent. Thus, the existence of randomness in the empirical world can never be more certain than our most certain observations.
So, the free will-determinism debate may never advance any futher.
There is speculation that true randomness, as apparently seen in certain quantum phenomena, may be the basis of free will.
I agree entirely with everything you say. I especially like the qualifications that you premise your statements with.
If randomness and free will are linked very closely and such things as weather patterns, water swirlings etc.. contain randomness then we are opening the door to either a Massive Universal Conscious entity - aka God - who may be in some way be influencing this phenomena, or a strange kind of small spontaneous free will that isn't additive or scalar, except when arranged in the physical structures that make up our brains.
I don't know that we can really speculate on which is more likely... I guess there could be both at the same time too - all these little randomnesses which are out of the control of God, but still add together to make up His Volition at a more macro level. This is kinda like us and our brains, which has been a general theme of the linked paper.