Question: Is it possible (like in star wars) to fuse someones body with fully mechanical organs, and survive, E.G. Darth Vadar?

We’re still in the early days, but we are beginning to create very usable prosthetic limbs that people can control using other muscles. We are learning more and more about how messages travel from the brain and how signaling between the brain and body works. This means that with some more advances in technology, we should be able to create working artificial hands, limbs etc.
As far as replacing the whole body, we’ve got a pretty long way to go. We have only just managed to create artificial blood that we can use for emergency transfusions, but it isn’t as good as the real thing. We have kidney dialysis machines that can do some of the work of a real kidney, but they’re about the size of a fridge. Heart-lung machines can keep people alive without a heart or lungs for a few hours during heart transplant surgery but they can’t be moved around and the blood cells are damaged more and more the longer the machine is used. As simple as it seems, the human body is incredibly complicated and does its job so incredibly well. It will be a long time before we can replace it all.