Re: quantum non-determinism
I assume that if the universe is non-deterministic at the quantum level, then we have free will
No - that just makes things non-deterministic.
Free will means that what you think/choose can affect the outcome. So, if you believe in multi-verses, the version of you that thought "yes" goes off down one path while the version that thought "no" goes off down another. But they can't contact each other, so can never detect this.
Which is part of the problem. Whether you do or do not have free will won't affect what you actually do as it can't be detected since to do so means you have to predict the future, then change it, at which point did you change things, or was your prediction wrong? Just like Gődel's theorem says, some things are unprovable...accept it and get on with life.