I am going to give my view of free will and quantum decoherence.

FREE WILL: Nah.

I'll start by saying that I don't believe in free will. If you say it is "the ability to make choices independent of deterministic physical laws" then I'd say that you don't have free will.  That means that I believe that every decision you ever have and will make is entirely 100% determined by the universe that came before that decision, focused in onto that outcome.  But keep in mind that it is YOU making the decision.  You were crafted by the universe before.  The universe is making the decision, the 100% fated decision, through you.  Could you have done otherwise without changing anything at all about the universe before the decision? I think not.  Therefore I believe most people will agree that I don't believe in free will.

Some people get tripped out or depressed by imagining that all their decisions are fated and think that their decisions don't matter. This is not correct. Your decisions DO matter. You have a huge number of degrees-of-freedom in determining what your decisions are going to be, and you are making those decisions. At the point of time that you make the decision, you are exactly what you are and can only make the decision one way.  But never forget that it is because of who you are. YOU are making the decision.

DECOHERENCE: disruption

As for quantum decoherence this is a lot more difficult to understand. On the easy side of the problem we have the fact that measurement causes outcomes to change, causes superpositions to decohere into single possibilities.  The double-slit experiment goes from a wave pattern to particle piles as soon as you look closely enough to gain any information about which slit the electron is going through.  This seems very weird but I think what is happening on this scale is that "looking closely" cannot be done without also "disrupting" the system. Any disruption will cause decoherence, it doesn't have to be "looking".

OBSERVATION:

On the hard side of the problem, whether decoherence happens or not seems to be tied into whether the observer is entanged with the system or not, which is to say you may have entangled observers that see superpositions while external observers see exact outcomes.

My explanation of this is wild and might be distrubing so please have alcohol at the ready if you need it.

POSSIBILITY SPACE:

I don't believe there is a physical univerese. It was always weird to me to think that there was Plato's heaven (numbers, math, concepts, probability, etc) and also a physical universe where the math could be used to describe the physics.  Why are things like this?  It is weird.

I think things are actually simpler.  Without a physical universe... if all that exists is math, concept, possibility... than what we think is a physical universe is really just one possibility within the mathematical set of all possibilities.  And so every moment we find ourselves in some point in possibility space.  That space is much larger than space-time.  Instead of a single space-time, there are infinite possible spacetimes.  Every universe that could exist (remember, even in Plato's heaven, possibilities must be self-consistant) does exist in some place in the possibility space.

So that leads to the question of why there seems to be a physical universe, why we seem to be at one point in the possibility space, which swings the question around to consciousness.

CONSCIOUSNESS:

We feel like we are moving through time. But we only exist at a single precise point in time.  Our feelings of past, our memories, exist right now as we recall them.  There may not have even been a past.  The very consistent progression of time as memories that the human animal experiences.  Your consciousness inhabits that possibility point.

Imagine if your consciousness is jumping between different people, different planets, different animals.  You would not be able to tell.  In each instant you would experence only what that animal is experiencing including it's memories at that possibility point.

And so I don't think time exists except as a causal dimension of possiblity space.

GOD:

I like to think of a single God inhabiting all possibilties.  That is our consciousness. In everything, everywhere, all the time, in all possibilities.  You are God inhabiting a human animal at a specific point in possibility space.

I'm an Animist.