Your second point equates to, "Well, we don't know everything about everything in the universe, so there might be a mechanism for free will we haven't discovered."
True, but that also applies to every other proposition that we can safely disregard because there's no good reason to accept it.
In the case of free will, we as potential authors of action need a lever for injecting ourself into the universe's chain of events. We need a hook. We need an influence point. But since we ourselves are products of that universe, such a mechanism is purely speculative.
The only reason we think free will exists is because we experience it. But given our understanding of the brain and its propensity for projecting all manner of illusions onto our consciousness, I submit we should not consider this evidence.
Show us how we have gained control over a previous state of the universe in one of the instants between the big bang and now, or show us how we can control the physics of transition from one state to the next.
Only then will one have made a case for free will.