1) We are in a simulation already. I agree with that. Reality is a simulation. I don't worry about that, because that statement changes nothing for me. It is like saying water is not water because it is simulated...and yet, I still need to drink it. Nothing is changed by calling "reality" a "simulation." All you are doing is substituting a different word...using a new word to describe the rules we continue to live by. Swapping out "reality" for "simulation" is a mere exercise in linguistics. It's marketing.
2) Maybe not. And yet, I enjoy the perception that I have free will. Either way, I don't worry about this either.
3) AI is inevitable. You are right that we should not worry about what is inevitable. A few years ago I changed how I view the world and our nation. I now view a lot of that in the same way I view Notre Dame football. I cheer. I hope one side wins. I hope people don't get hurt. But, I don't fool myself. I have no direct effect on any of that, and any indirect effect I have is minimal at best, insufficient to turn a steaming aircraft carrier. But, I can change how I live, and how I raise my family. For example, I can buy a better wine next time I'm at the store. And, I still dream of buying a cabin in the woods.