Sorry I don't have much time to respond to anything right now since I'm travelling. The easiest framework where you can see how this can work out is in quantum field theory which unites quantum mechanics with *special* relativity. Here, one finds that even though things look nonlocal at the level of wave functions mathematically, all physical observables you can calculate turn out to be limited by light speed. Indeed, virtual particles and antiparticles conspire to make information transfer with faster than light impossible. Now, if you have quantized spacetime, I would say things become seriously messy, but if you still use the copenhagen approach to quantum theory, it may be that although the maths may look nonlocal, also there locality arises in the end dynamically.
As far as locality in holographic theories is concerned, interesting question, don't know at this moment!
As far as locality in holographic theories is concerned, interesting question, don't know at this moment!
